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Arthur Mitchell

Arthur Mitchell Wolf in Sheep's Clothing

"I couldn’t care less about your life. Or death. Unless you get in my way." ~Arthur Mitchell ("The Getaway")"

Arthur Mitchell aka The Trinity Killer is the Main Antagonist in Season Four of the Showtime series DEXTER.

Arthur was a suburbanite who lived a double life as one of America's most prolific serial killers for three decades. He was thought by the FBI to be a mere "myth" chased by Special Agent Frank Lundy.

He also briefly appears in Dexter: New Blood in a podcast photo ("H is for Hero") and in flashbacks ("Skin of Her Teeth").

The Trinity Killer

A pattern of killings that continued for fifteen years was first noticed by Special Agent Lundy, but he was unable to identify the perpetrator. Then, in "Living the Dream," Lundy discovered an additional fifteen years of kill cycles, dating back to Vicky Noonan in 1979. Lundy had initially thought that each kill cycle consisted of three murder victims, and so had dubbed the perpetrator as The Trinity Killer. Later, Dexter Morgan discovered that each cycle actually consisted of four murders. The 'missing' ritual involved the live burial of a ten-year-old boy at the beginning of each cycle, per "Lost Boys". (See: Trinity Case)


Before Arthur died, he was a man in his early 60s with white-gray thinning hair, blue eyes, as well as an imposing height and build. In spite of his age, Arthur possessed a considerable amount of strength, which was seen when he held a strong individual like Dexter in a chokehold and overpowered his athletic son, Jonah, with startling ease.


When on the job (at the dig sites), he preferred a T-shirt and blue jeans, as well as work boots and equipment used for the dig. When teaching at school, he wore much more formal attire befitting his occupation as a teacher. This formal attire was also seen when he went to church. It could include tan-colored or gray suits that remained unbuttoned. He also frequently wore mirrored sunglasses.

On the night that he kidnapped Tarla Grant, he wore dark clothing. When he bludgeoned Earl Doorman, he wore a blue jumpsuit, along with a face shield and plastic gloves to prevent being sprayed by blood.


"You can't control the demon inside of you any more than I could control mine." - Arthur Mitchell ("The Getaway")

Being "born in blood" (Dexter's euphemism for psychological trauma leading to homicidal impulses), coupled with Arthur's longevity as a successful serial killer, made this man incredibly complex. Arthur's life was comprised of schedules, routines, and identical kill cycles. If something did not go according to his plan, he found it difficult to improvise. Possibly due to his age or his increasing lack of humanity, the boundaries compartmentalizing his life started to crack. His moods would switch at random, and he was easily angered. As quoted by Dexter himself, "Yesterday he was jumping down my he is a happy dancing man. Is that mask of his crumbling?"

The Family Man

For decades, Arthur lived as a devoted family man, church deacon, beloved teacher, community volunteer, and model citizen. He took pride in his house and car and kept them perfectly maintained. Extremely protective of his sister's ashes, Arthur didn't allow anyone to touch the urn. No one suspected that he was a prolific serial killer.

Because of his pristine reputation, Arthur became very defensive when Dexter called him a pedophile.

The Abuser

Despite his public persona, Arthur was extremely controlling and abusive behind closed doors, prone to outbursts and tirades. His family did whatever was necessary to keep him happy. They looked forward to the times when Arthur would go out of town.

Arthur was especially controlling with his teenage daughter, Rebecca, whom he called “Vera” (the name of his dead sister). Arthur often locked Rebecca for hours in her bedroom, which was decorated for a young child.

Jonah took the brunt of Arthur's physical abuse. He frequently hit Jonah, who had to hide his bruises from his gym teacher. For this reason, Jonah quit school baseball, causing Arthur to destroy his son’s sports trophies. He even broke Jonah's pinkie finger because he damaged Arthur's car. At times, Jonah dared to fight back, either verbally or physically, which enraged Arthur.

Although Sally loved her husband, she feared his unpredictable moods. She never deliberately provoked Arthur, and pressured the children to adhere to his rules.

The True Arthur

At times, Arthur had a hard time accepting his true self. This seemed apparent when he was faced to kill a wounded deer and began to cower, as if he had never picked up a weapon before.

Arthur claimed to dislike the "demon" inside himself, and said that he didn't enjoy killing. Eventually, to stop himself, he decided to commit suicide and secretly built his own coffin in preparation. During a planned trip to a Tampa build site, Arthur attempted to fall to his death, much like his mother. However, this was prevented by Dexter. Arthur then acted as if new life had been breathed into him and he praised Dexter, believing that God sent him to save his life.

During a mishap on Thanksgiving, in which Dexter almost killed Arthur in his own home, a terrified Arthur didn't fight back.

Later, while Arthur was on the hunt for "Kyle," he was shown to be cold and calculating. Seeming to enjoy the game, he talked to Dexter in a cheery voice on the phone.

When Arthur ended up on Dexter's kill table, he accepted his death as God's will.


Arthur Mitchell was born in Tampa, Florida, and lived in a two-story house for most of his young life. One day in 1959, an event forever scarred him. As a curious ten-year-old boy, he stood in the bathroom doorway, watching his elder sister, Vera, take a shower. When she noticed him in the mirror, she slipped, shattering the shower doors. A shard of glass sliced her leg and she bled out in front of him. It was a hard blow to the entire family, and they moved to Miami. His mother, Marsha, grew increasingly depressed, culminating in her suicide by jumping off a bridge in 1960. This left Arthur alone with his alcoholic father, Henry, who was verbally and physically abusive. In 1964, Henry was found bludgeoned to death in an alley near a bar (presumably by Arthur, who was nineteen at the time).

After graduating college, Arthur worked as a high school teacher. He met Lorraine Hill and they had a daughter. After Arthur's relationship with Lorraine ended, he and Christine only met on holidays and her birthday.

Arthur then married Sally and they had two children -- Jonah and Rebecca.

At an unknown point, Arthur joined the organization known as Four Walls One Heart, which built houses across the country. He began to use these travels as an alibi for his kill cycles.

Kill Cycles

With his original family long gone in a tragic past, Arthur often reminisced about them. In fact, the four victims in each of his kill cycles represented himself, sister, mother, and father.

Due to his life as a teacher, Arthur often carried out kill cycles during school holidays while he was out of town with Four Walls One Heart. The plaques he received for his part in building new homes served as his trophies. After finishing a kill cycle, Arthur would return home, happy and and relaxed, for a "cool-down" period.

Arthur was careful to never leave a trace of his presence at the scenes, aside from a smudge of Vera's ashes.

Each cycle consisted of four distinct M.O.s.

  1. Ten-year-old boy is buried alive. He represented Arthur as an "innocent" before he witnessed the death of his sister. Arthur referred to the boy as “Arthur,” forcing him to wear pajamas and play with a toy train. He then drugged the boy and buried him alive in wet concrete at a Four Walls One Heart site. It was Arthur's way of symbolically preserving the innocence that he lost.
  2. Young woman bleeds out in a bathtub. She represented Arthur's sister, Vera, who had slipped in the shower and sliced her femoral artery after he startled her. To remember Vera’s death, Arthur would force a young woman to lie naked with him in a bathtub. He then cut her femoral artery and held up a mirror to watch her face as she bled out. Afterward, Arthur took a scalding hot shower elsewhere, likely to wash away his sins.
  3. Mother of two jumps to her death. She represented the suicide of his mother. By using threats to her family, Arthur coerced a mother to commit suicide. He was extremely particular about making the woman fall on her own, rather than him pushing her. He then addressed her body as "Mommy" and briefly grieved.
  4. Father of two is bludgeoned. The final kill represented the death of his father. Because of his deep hatred for his father, it was arguably Arthur's most violent and sadistic kill in the cycle. Before Arthur carried out this kill, he would share a drink with his long dead father, across from an empty chair. Arthur then willed himself to go to a local bar in order to have himself beaten senseless, while yelling insults at his attacker. This depicted the abuse that he had endured from his own father.

Cycle Victims

List of victims killed in Season Four. For a full list of Cycle Victims, see: Trinity Case.

Non-Cycle Victims

Trinity usually did not kill outside of his well-established cycle, and generally posed no threat to anyone once the cycle was completed. However, there were exceptions.

  1. Henry Mitchell - Arthur's father. Due to the profanity that Arthur shouts while bludgeoning the men, it's probable that Henry was Arthur's first kill.
  2. Kyle Butler - His name was the same as Dexter's alias. Kyle caught Arthur breaking into his house and threatened to call the police, Arthur killed him in order to silence him. ("Hello, Dexter Morgan")
  3. Rita Morgan - A bathtub victim. She was not part of a kill cycle for two reasons. Arthur had yet to succeed in burying a young boy in cement, and Rita wasn't a young childless woman. When Arthur found out where Dexter lived, Rita became a victim of circumstance. ("The Getaway")

Attempted Victims

  1. Himself - failed to commit suicide from falling, like he forced some of his female victims to do ("Road Kill")
  2. Jonah Mitchell ("Hungry Man")
  3. Scott Smith ("Lost Boys")
  4. Kyle Butler ("Hello, Dexter Morgan")
  5. Possibly Dexter Morgan, after Dexter drugged him and stole his money ("The Getaway")

Indirect Deaths

  1. Vera Mitchell - She was startled by young Arthur while she was taking a shower and accidentally sliced her femoral artery. (mentioned, ("Road Kill")
  2. Frank Lundy - He was shot by Christine Hill, who tried to prevent her father from being caught. ("Dex Takes a Holiday")
  3. Stan Beaudry - He was killed by Dexter because he needed to frame someone for Trinity's murders. {"Hello, Dexter Morgan")
  4. Christine Hill - She committed suicide by shooting herself after police realized she killed Lundy, and Arthur rejected her. ("Hello, Dexter Morgan")
  5. Rebecca Mitchell - She committed suicide in a fashion similar to the bathtub victims. ("Nebraska")
  6. Sally Mitchell - She was killed by Jonah Mitchell because her abusive behavior resulted in Rebecca's suicide. ("Nebraska")

Alleged Victims

  1. Frank Lundy - Initially thought to be a victim of the Vacation Murderers, and then by Trinity. Later, it was confirmed that he and Debra were shot by someone shorter than Trinity.
  2. Rebecca Mitchell - Committed suicide in a bathtub, but Debra believed that Trinity killed her.
  3. Sally Mitchell - Bludgeoned by Jonah Mitchell, but Debra believed that Trinity killed her.
  4. Stan Beaudry - For a time, he was a Trinity suspect. Later on, because Dexter had planted Arthur's DNA in Stan's home and truck, the police may have blamed Arthur for Stan's disappearance.


After dark, Arthur breaks into Lisa Bell’s house. He flips on the light in the bathroom, fills the tub with water, removes his clothes, and lays a towel on the floor. Then he waits for Lisa to return home. When she enters the bathroom, she notices the reflection of a naked man in the cabinet mirror and screams. Arthur instantly grabs Lisa in a chokehold and forces her to lie naked with him in the bathtub. She struggles but he subsues her, and says, “It’s already over.” Next, he picks up a straight razor and slits her femoral artery. As the water turns red, Arthur holds up a mirror and watches Lisa's face as she dies.

The next day, the homicide team arrives at Lisa’s place. Dexter notes that the killer took his time and thoroughly cleaned up after himself. Outside the house, Det. Joey Quinn is questioned by Christine Hill, an attractive reporter. She flirtatiously presses for information and he gives her his phone number.

During a return to the house, Dexter and Karen (a tech) discover older blood under a bathroom tile, apparently from a previous crime. Dexter is taken off guard when Frank Lundy unexpectedly appears and greets him. When Dexter confirms that Lisa’s femoral artery was severed and the killer was meticulous, Lundy asks to meet with him later.

At the station, Vince Masuka informs Dexter that Lisa’s DNA doesn’t match the old blood found in her bathroom. To their surprise, they discover a similar homicide at the same address in 1979. A woman, Vicky Noonan, had bled out in the bathtub from an incision to her femoral artery.

Lundy drops by to speak with Dexter alone. He reveals that he’s retired from the FBI, and now has time to track down the “twisted son of a bitch who got away.” Because the elusive murderer kills in threes all over the country, Lundy has dubbed him The Trinity Killer. Lundy believes that Trinity is in Miami, starting another kill cycle. When Dexter informs him of Vicky Noonan’s murder, Lundy realizes that Trinity has been killing for at least thirty years. Dexter remarks, “Trinity is the most successful serial killer to ever get away with it.”

Moaning and grimacing, Arthur is taking a scalding hot shower in a locker room.

Arthur is sitting outdoors at the Daybreak Cafe, drinking coffee and solving a crossword puzzle, when two women walk by. One of them catches his attention and he follows her. At one point, the woman’s son bumps into Arthur, smearing his arm with ice cream. The boy apologizes and Arthur ominously says, “You better catch up with your mom. You don’t want to lose her.” He continues to stalk the woman, noticing her affection for dogs.

Debra and Lundy question Eddie Noonan, an ex-con who was convicted of the murder of his wife, Vicky Noonan. Afterward, Deb and Lundy agree that Eddie likely didn’t kill either Vicky or Lisa.

It’s after dark. Arthur is walking a dog down a sidewalk when the woman he was following earlier approaches, carrying groceries. He introduces himself as Alan, a neighbor. While she’s petting Arthur’s dog, he learns that her name is Tarla and she owns a “calm” puppy. He helps carry the bags to her house and they part ways. Having gathered information for his next kill, Arthur releases the dog into the streets.

Tarla, weeping, is forced by Arthur to drive to an empty warehouse. When they arrive, he takes her to the top floor and tells her to jump. When she resists, he threatens to kill her family. Trembling and sobbing, Tarla lets herself fall to her death. Arthur looks down at Tarla’s body, seemingly horrified. After climbing down the stairs, he stands next to Tarla and whimpers, “Oh… Mommy,” Arthur takes out a small glass vial, removes a glove, licks his finger, dips it inside, and wipes a smudge of ashes next to Tarla’s hand. He then walks away, leaving Tarla’s car at the scene.

The next day, police assume that Tarla committed suicide, but Lundy is doubtful. During a lunch break, Debra shows the files of Lisa Bell and Vicky Noonan to Lundy.

Back at the warehouse, Mauska throws dummies off the top floor while Dexter and Lundy discuss Trinity. Lundy believes that he's been a successful killer because he’s a lone wolf, having foregone all but the most rudimentary of human connections.

In Arthur’s house, a small wooden table holds a whiskey bottle, a pitcher of water, two glasses, and two framed black-and-white photographs: one of a young girl, the other of a happy couple. Arthur places a decorative urn on the table into which he pours the ashy contents of a small vial. After sitting down in one of two chairs, he slowly pours a glass of whiskey and a glass of water. He pushes the whiskey across the table, and clinks it with the water glass. “Drink up. You’re next,” he solemnly tells the empty chair.

Arthur is sitting at a library computer, looking at photographs and blueprints of an office building. He shushes a group of teen girls, and then notices a newspaper headline about Lundy returning to Miami to hunt a serial killer.

After dark, Arthur lies in wait behind a tavern. The first man to emerge is joined by a woman, so Arthur ignores him. When the second man exits, Arthur steps from the darkness and calls him a “cunt.” The man turns and asks Arthur what he just said. “You’re a cunt,” Arthur repeats. The man says to eff off, but Arthur provokes him, by calling him a “fucking pussy.” The man then punches and kicks Arthur, who persists in his name-calling. When Arthur declares, “It’s your fault… all your fault,” the disgusted man stumbles away. Arthur rises to his feet, with a look of determination.

Lundy is speaking into a tape recorder outside the office building that replaced the tavern where a beating victim died thirty years ago. Arthur exits the lobby door, spots Lundy, and retreats behind a pillar, whispering, “I’m found.” Then he braces himself and walks past Lundy, sideswiping him. Arthur apologizes and keeps on walking. Lundy notices that Arthur dropped his keys. He picks them up, calls out, and returns them, Lundy then follows Arthur until he hops on a bus. Lundy records the encounter with a description of the stranger. (Later, it’s revealed that Christine Hill is watching them.)

At the end of the episode, Debra and Lundy are gunned down and robbed outside his hotel. In the next episode, i

Arthur is sitting in a diner, watching news of Lundy’s murder on a TV. The waitress delivers his Denver omelet, but it doesn’t contain diced tomatoes, so he insists that she start over. With a forced smile, she complies and he calls her a “dear.”

At a hardware store, Arthur is having difficulty picking out a hammer. The salesman recommends the framing hammer, and Arthur thanks him for his help.

Outside the office building, Dexter is sitting in his car, listening to Lundy’s tapes. Thirty years ago, a man was found bludgeoned to death on this site and he thinks Trinity will strike at the same place. However, Dexter has no physical description, so he doesn’t know who to look for. He suspects there is still another tape being held in police evidence.

Posing as a recently laid-off man, Arthur is given a tour of the office building by a security guard. A friendly counter man pours coffee for the guard and offers Arthur a cup, but he refuses, saying, “Caffeine makes me a different person.” Arthur learns from the guard that he makes a forty-five minute round every two hours. On his way out, Arthur’s jovial facial expression vanishes.

That night, Arthur enters the office building, carrying a black duffel bag. Dexter turns up and notices that the security guard isn’t at his desk. Running inside, he hides when the guard exits the elevator. To distract him, Dexter hits an elevator button and sends it to the twelfth floor.

On the fourth floor, Arthur lowers a face visor as the counter man pleads, “I’m a father.” Arthur leans in to say, “You were no father,” and then repeatedly bludgeons the man’s head with a hammer. Meanwhile, Dexter breaks into the surveillance room and discovers the recording disk is gone. He frantically scrolls through the screens until he sees Trinity beating the man to death. When Trinity takes off his blood-spattered visor, Dexter gets a clear view of his face. He watches Trinity move the victim’s arms so they’re spread out at his sides.

Dexter races up the stairs, but the fourth floor door is locked. After hurrying back to the lobby, he notices that the elevators aren’t moving, so Trinity must have taken stairs. He runs outside just as Trinity drives off in a gray van. Dexter quickly follows him in his car, likening Trinity to a “rat scurrying back to his hole.” He’s perplexed when Trinity heads out to the suburbs.

In a residential neighborhood, Trinity pulls into the driveway of a brightly lit house. Dexter thought, He doesn’t belong here. It doesn’t make sense. As he approaches Trinity with a syringe of M99, a woman suddenly opens the door and they warmly hug each other. Through the window, Dexter watches Trinity lovingly greet a girl and a boy. Lundy was wrong. I was wrong. Trinity is a husband, a father. He’s... like me.

On Sunday morning, Arthur leads a rendition of “Are You Washed in the Blood” in church. Dexter is among the parishioners, singing along. For days, he’s followed Arthur to learn his schedule.

The office building reopens after the weekend and Earl Doorman’s body is found. Masuka determines the cause of death is blunt force trauma to the head from a framing hammer. Blood spatter indicates that the killer was over six feet tall. Dexter remembers that Arthur moved the victim’s arm to point to a smudge of ash on the wall. When he tries to collect the sample, Masuka demands it.

At church again, Arthur and his family are listening to the sermon. From a nearby pew, Dexter watches as they display affection for each other. He decides to delay murdering Arthur so he can learn from him.

As the parishioners depart, Arthur hands out flyers for “Four Walls One Heart.” Dexter takes one and introduces himself as “Kyle Butler.” He claims that his wife kicked him out of the house and took the kids. Arthur assures “Kyle” that he’s come to the right place.

While looking at the flyer in his lab, Dexter decides to skip work and stalk Arthur. Before he leaves, Masuka reveals that the killer is related to the cremation ashes.

At a build site, Arthur is hammering a nail into the frame of a new house. Nearby, his family is helping out. When Arthur catches sight of “Kyle,” he jovially greets him and hands him the same hammer he used to kill Doorman. Dexter notes the make and model before nailing a beam into place. Spotting Arthur’s son by the water cooler, Dexter walks over and introduces himself. Jonah praises his parents and says his father just gave him his prize convertible. “Best dad ever,” Jonah states. Just then, Arthur looks their way and Jonah hurries off, explaining that his father doesn’t like idle hands.

Afterward, Dexter is dropped off at Arthur’s house. When Arthur isn’t looking, he slices his knuckle with a box cutter and lies that he cut himself at the build site. Arthur hangs up the hammer on a wall in the garage and leads Dexter into the house, insisting they take off their boots at the door.

Arthur goes off to get the first aid kit after telling Dexter to make himself at home. As Dexter wanders around, he spots several wall plaques that commemorate Arthur’s work for Four Walls One Heart. Since their dates and locations correspond to kill sites in Lundy’s books, Dexter realizes they are trophies. He notices Vera Mitchell’s cremation urn and looks inside. He’s holding it in both hands when Arthur bounds into the room. Arthur stops short, takes the urn from Dexter, and places it on the table. Grimacing, Arthur charges forward, and pins Dexter to the wall with his forearm across his neck. “Don’t … touch … my sister!” he sputters. When Dexter gasps that he can’t breathe, Arthur releases him and apologizes. Dexter feigns shock and Arthur explains his behavior by saying that his sister died when he was young and it was very painful for him. Dexter assures Arthur that he understands because he’s lost people, too.

While Arthur bandages his wound. Dexter asks why the ashes are kept out; Arthur says his sister is a part of him. He goes on to tell Dexter that he used to push people away, which led to the loss of a relationship. Then he met his wife and realized it would only work if he “jumped in with both feet.” Dexter repeats the phrase, and asks if that saved his family. Arthur replies, “Kyle, my family saved me.”

As Dexter is leaving, Arthur gives him a bag of tools, which includes the framing hammer. Dexter thanks him and they agree to meet at the next build.

Later, Arthur stealthily opens a bathroom door. His wife is soaking in the tub, and she notices him watching her. “You always catch me,” Arthur jokes. He joins her in the bathtub and puts his arms around her. He then picks up a hand mirror, and holds it up to see his wife’s face. “Look how beautiful you are,” he tells her. She smiles, leans her head on his arm, and closes her eyes. Arthur lowers the mirror into the water.

Dexter purposely “bumps into” Arthur outside a hardware store. He assists Arthur in loading his van and asks why Jonah isn’t there to help. Arthur says that he’s busy, and advises Dexter to encourage his kids to have outside interests. Dexter sees how that strategy would benefit a serial killer. When Dexter claims to be new in town and doesn’t know anybody, Arthur tells him to meet at his house the next morning.

At daybreak, Arthur takes Dexter for a drive in his van through a forest, stopping at an isolated area. Arthur opens the back of the van and reveals an array of cutting tools. “Choose your weapon,” he tells Dexter. Given his expertise with the chainsaw, Dexter chooses the ax. Arthur takes a chainsaw, a hacksaw, and a regular saw, and they walk further into the woods. Dexter learns that Arthur plans to cut down a tree. However, Arthur is unable to start the chainsaw. He curses and throws his hands up in the air. Dexter offers to help and easily starts the chainsaw with one pull and repeatedly revs it. Not handing back the chainsaw, Dexter fells a tree with one clean cut, which annoys Arthur.

Arthur begins to measure the tree, and Dexter asks what to do if a kid isn’t interested in his suggestions for outside activities. Arthur angrily replies that they shouldn’t be suggestions. “They’re just children, Kyle. You let them do whatever they want, they suck their thumbs and diddle themselves all day.” When Dexter asks why he doesn’t just buy lumber from the hardware store, Arthur snaps that this wood is better.

Driving home, a deer jumps out of the bushes and slams into the front of the van. It’s seriously wounded, and Arthur stares at it with horror. He gasps that he didn’t mean to hit it, and wants to leave it there. However, Dexter insists they put it out of its misery. He hands the ax to Arthur, but Arthur can’t kill it, which Dexter finds strange. Dexter offers to do the deed, which relieves Arthur. As Dexter prepares to deliver the fatal blow, Arthur turns away and Dexter is tempted to kill him. Instead, he takes one swing which kills the deer.

In his garage, Arthur is obsessively sanding a plank, made from the tree that Dexter cut down. Later, Arthur is seen fitting two boards together, looking fatigued and troubled.

In his garage, Arthur Mitchell is hunched over a newly-made coffin in prayer. He then caresses the wood and covers it with a tarp.

Dexter (still going by Kyle Butler) drops by Arthur’s house under the pretext of being worried about him; Arthur claims to be fine. When Arthur chastises his son for not waxing the car correctly, Dexter notes the "small cracks in the perfect family." In a few minutes, Arthur reprimands his daughter for not watering the flowers correctly.

Arthur's wife, Sally, brings him a glass of pink lemonade and mentions that his clothes are ready to be packed. Dexter learns that Arthur is going to a build site in Tampa the next day, without his family.

Dexter obtains permission from Lt. LaGuerta and his wife to supposedly attend a meteorological conference in Tampa.

That night, Dexter packs light for the trip, only bringing Arthur’s hammer and a large knife. Meanwhile, Arthur is pouring the last of Vera’s ashes into a small glass vial. He tucks it in among his clothes and shuts his suitcase.

At the end of the school day, Arthur is about to take off on his Tampa trip when Dexter suddenly appears outside his van. Arthur refuses to let “Kyle” go with him, but Dexter insists that he needs to get away. Arthur relents when Dexter says that he gives him a sense of purpose, and remarks on his generosity of spirit.

During their ride, Arthur questions Dexter but he’s met with curt answers. Dexter only says he made a big mistake, and Arthur accuses him of being purposely vague.

At Dexter’s request, Arthur pulls into the Collier County Rest Stop. While Dexter eats a burrito from a vending machine, Arthur sips a soda. He pressures Dexter to reveal his problem, saying that he wants to help because good deeds are rewarded by God. When Dexter remains reluctant, Arthur loses his patience and threatens to drive away and leave “Kyle” to fend for himself. Dexter quickly states, “I killed a man.” This gets Arthur’s attention. Dexter calls it a “hunting accident” and blames himself. Arthur says remorse is what separates us from the animals, and confession is good for the soul.

Dexter chooses his hotel room’s bathroom as the place to kill Arthur. As he’s looking up a hardware store to buy supplies, Debra calls to ask about his discarded crime scene photos to see if Trinity left an ash smudge near Tarla Grant.

Dexter finds Arthur standing outside his door, poised to knock. He cheerily informs Dexter that they won’t be going to the build site in the morning. Instead, he’s got a surprise that will make him feel better. Dexter wonders what kind of surprise.

Waking early, Dexter leaves to establish an alibi at the conference before Arthur’s surprise outing. However, Arthur is already waiting in the parking lot, holding two coffees. He’s so excited that he does a little tap dance. Dexter is puzzled by the drastic change in Arthur’s behavior and wonders if his mask is crumbling.

Arthur parks at a small suburban house, runs to the door, and frantically knocks and rings the bell. An Asian man thinks they are salesmen, but Arthur says he grew up in this house. Ignoring the man’s protests, he bounds up the stairs. Dexter bows to the couple and runs up after Arthur.

Arthur is standing at the bathroom door. This is where it all started, Arthur says. He goes on to tell Dexter that when he was ten, he was innocently watching his sister, Vera, take a shower. Vera was startled when she saw him in the mirror, causing her to slip, shatter the shower doors, and slice her femoral artery. Before the ambulance arrived, Vera had bled to death. Born in blood, Dexter thought. Both of us. Arthur was blamed by his parents for her death. Overcome with depression, his mother killed herself. His alcoholic father would beat him and call him a pervert. When Arthur says his father is dead, Dexter suspects that Arthur killed him. Embracing Dexter, Arthur asks if he feels better. The Asian couple threaten to call the police, and Dexter persuades Arthur to leave, by suggesting lunch at a “great place.”

Dexter and Arthur are seated in a hotel coffee shop, Under the ruse of using the restroom, Dexter ducks out into the lobby, where the convention is being held. He signs up as proof that he attended and takes a photo with a weatherman. Dexter promptly returns to the coffee shop. However, Arthur isn't at their table. Instead, he's sitting in a corner booth with a clearly uncomfortable family of four. Arthur is on a tangent about speaking the truth and he invites Dexter to confess his own sins. Instead, Dexter forces Arthur to leave the family in peace.

Once outside, Dexter suggests stopping at a hardware store to pick up items for donation to the Four Walls build. They purchase plastic sheeting and drop it off in Dexter’s hotel room.

After Arthur leaves, Dexter sets up a kill room in the bathroom. He then takes out a hypodermic containing M99, and breaks into Arthur’s room by picking the lock. Unfortunately, Arthur is not there. Arthur’s van is in the parking lot, but his work tools aren’t inside. Dexter takes off running to the build site. As he stalks through the partially built house, he hears the thud of Arthur dropping his tool belt.

Looking up, he sees Arthur standing on the edge of the roof. As Dexter creeps toward him with his M99, Arthur empties the last of his sister’s ashes onto the ground below. Dexter grasps Arthur’s intent when he spreads his arms and steps closer to the edge. Dexter quickly grabs Arthur as he falls, but Arthur begs Dexter to let go. Dexter weighs whether to keep him alive just to kill him. He’s about to let Arthur slip from his grasp when construction volunteers run over and hoist him back up to the roof. Now safe, Arthur looks over at Dexter and gasps, “I thought God sent you so that I could save you. But God had another plan. He sent you to save me. Not exactly, Dexter thought. Dexter is viewed as a hero, as he secretly vows to not spare Arthur again.

On the way back to Miami, Arthur asks Dexter to think of his fall as a “little accident.” He assures Dexter not to worry about him, saying that he’s embarrassed, but not suicidal. Nearing the city, they approach a police checkpoint. Dexter tells Arthur they are looking for a “huge serial killer” and have his DNA. Arthur’s face betrays nothing, and he turns around to take the scenic route. As he drives away, Arthur begins to laugh.

Dexter is parked outside Arthur's house. Through a window, he watches Arthur break his son’s baseball trophies as punishment for quitting baseball. Jonah storms out of the house and drives away in his father’s prized convertible. Dexter follows Jonah to a deserted area and finds him beating the car with a baseball bat.

Jonah admits that his father is abusive and he quit baseball because he couldn’t explain the bruises to his coaches. Jonah then states, “You should have just let him die” (referencing Arthur’s failed suicide attempt). Dexter offers to go with Jonah when he breaks the news to Arthur about the damaged car. This seems to relieve Jonah and he invites “Kyle Butler” to his family’s Thanksgiving dinner the next day.

When Arthur collects his morning paper, he’s drawn to the headline: OCEANGATE BLUDGEONER REMAINS AT-LARGE. The journalist’s name is Christine Hill.

Dexter (as Kyle Butler) shows up at the Mitchells’ door, holding an offering of store-bought cookies. Arthur and Sally’s demeanor is less than welcoming, but he just stands there awkwardly. When Dexter says it’s the first Thanksgiving without his family, they relent and he’s allowed inside..

Dexter begins helping Arthur and Sally prepare the meal. Arthur grumbles that Jonah seems to have forgotten the holiday. His wife assures Arthur that Jonah knows how important Thanksgiving is to him and he will be there. In response, Arthur gives her a cold look. Sally then asks if Rebecca can “come out now” and a scowling Arthur goes to get her. Dexter asks Sally if Rebecca is grounded, and she only replies that it’s “nothing like that.”

Arthur escorts Rebecca out of her bedroom and she politely greets Dexter as “Mr. Butler.” He invites Dexter to a pre-game football toss, as Rebecca heads for the kitchen. Arthur remarks that he has at least one perfect child.

Out in the garage, Arthur can’t find the football and Dexter suggests a baseball. Arthur finds that ridiculous and expounds on why traditions matter. Just then, Dexter discovers Arthur’s coffin and he admires the craftsmanship. Arthur says he’ll likely donate it to charity, since he won’t need it. No, you’ll be buried at sea, Dexter thought.

Jonah’s football is found, but it’s deflated. This disgusts Arthur and he chalks it up to his son’s irresponsibility.

At that moment, Jonah arrives home, driving the damaged car. He lies to his father, saying that the car was trashed during the night while in his friend’s driveway. Angrily, Arthur walks to the garage and returns with a crowbar. He wedges it into the wheel well, pulls out a dent, and declares that the car is now fit to drive. Arthur’s mood lightens and he cheerily invites Dexter and Jonah to watch the football game.

During the plays, Arthur yells at the television, but Jonah remains calm. Thinking that Jonah is safe, Dexter excuses himself. His first stop is Rebecca’s room, which is strangely decorated for a young child. More disturbing are the locks on the window and the door.

Dexter wanders into the front yard, where Rebecca is cutting roses. He asks about the locks and, startled, she says they are there to "protect" her.

In the living room, Arthur cheers a good play. While high-fiving his son, he grabs Jonah’s hand and twists a finger until it breaks. Utterly cool, Arthur tells him it’s punishment for the broken windshield, adding that beautiful things should be honored. Arthur then walks over to Vera’s urn to polish it.

Outside, Rebecca tells Dexter that she once ran away, with terrible consequences. She flirtatiously asks if she can stay with him and says she’ll do anything he wants. Taken off guard, Dexter insists that he doesn’t want anything from her. Rebecca leans in for a kiss, just as Sally appears and orders her into the house. A terrified Sally tells Dexter that she doesn't care what he does with her daughter, but begs him not to tell Arthur. She hurries back inside, leaving Dexter appalled.

Dexter receives a call from Rita. He learns that Cody fell through the roof of his shed and Elliot took off the door to get him out. The boy is unhurt but, with his secret space exposed, Dexter is eager to get home.

Back into the living room, Dexter spots Jonah taping up his finger. He claims to have hit his hand against the table. Arthur just laughs, “My son the klutz.” Dexter sits down, deciding to stay.

At the dinner table, the Mitchell family and Dexter hold hands as Arthur says grace. While he carves the turkey, Arthur tells Dexter about their family tradition where each of them lists the things they’re thankful for.

Arthur starts by saying he’s thankful for his family. Sally is thankful for the lovely home and her kids. Rebecca is thankful for an extension on a school paper and for the nice home. Jonah is thankful for the home and for God. Arthur sarcastically adds that he’s thankful for his car and gives Jonah a disapproving look. “Kyle” quickly mentions that he’s thankful for yams and for the comfort of their home.

Due to everyone mentioning the house, Arthur remarks, “Where no one said they were thankful for me.” Jonah admits that he’s not thankful for his father. When Sally tries to diffuse the situation, Arthur retorts, “Shut up, cunt.” Dexter protests and Arthur suggests that he leave, but Dexter thinks he should stay. Jonah blurts out, “Yeah, sure. Stay. Watch the show.”

Rebecca insists that she’s thankful for her father, and Arthur orders her to go to her room, calling her "Vera." Anger spews out of Jonah. He yells that she is not Vera, nor is she a prisoner or still eight years old.

Jonah grabs a Four Walls One Heart plaque and shatters a mirror with it. Next, he calls his father a “killer” and accuses him of sucking the life out of his family. Infuriated, Arthur lunges toward Jonah. Rebecca interferes, but her father tosses her across the room. Jonah holds up Vera’s urn and states, “Fuck you, and fuck Vera.” He then tosses it across the room, breaking it. Arthur attacks Jonah, pushes him down in a chair, and tightens his hands around his neck. Sally and Rebecca fearfully hold on to each other.

Dexter takes off his belt, wraps it around Arthur’s neck, and drags him to the kitchen. There, he slams the door and grabs a large knife. He holds Arthur down on the floor, and says menacingly, “I should have fucking killed you when I had the chance.” Sally and Rebecca burst in and scream at the disturbing scene. They throw themselves at Arthur and they embrace each other. Arthur appears to be terrified and Dexter quickly walks out, past a stunned Jonah.

While driving home, Dexter berates himself for revealing another side of himself, and insists that he’s nothing like Arthur, who uses his family as human shields.

Later, Quinn has just left Christine’s apartment when there’s a knock on her door. Whispering, “Joey,” she skips back to let him in. However, it’s not Quinn. It’s Arthur. “Hey, Dad,” she merely says.

t’s after dark and Dexter is packing up his kill tools inside a shipping container at Miami Shores Storage. He then follows Arthur to a parking garage and begins to watch him. Arthur notices a nanny leading a boy and a girl into an arcade and memorizes the family’s names from decals on their car decals. When Arthur begins to stalk them, Dexter assumes the young woman is his target.

At one point, the little boy goes off alone to play a game, and Arthur uses the info from the car decals to con him. He approaches the boy, calls him by his name, flashes a badge, and lies that his parents have been in a car accident. He insists that Scott go with him to the hospital, assuring him that his sister is already in the patrol car. Scott believes Arthur and accompanies him to the parking garage. However, when Scott sees the van, he realizes that Arthur is lying, but it's too late. Arthur chloroforms him and shoves him into his van. Dexter tries to unsuccessfully stop the kidnapping but Arthur squeals out of the garage.

Dexter runs back to his car and receives a phone call. It’s Arthur who warns “Kyle” that he will preserve the boy’s “innocence,” but if he sees a police car, he’ll kill him. Arthur states that he has a process to follow and afterward, he’ll set the boy free. Dexter, though, thinks the boy will die. He has never known Arthur to take a child before and wonders if this is something new.

Dexter finds Jonah home alone and he learns that Arthur is on a trip for a couple of days. Vera’s urn has been restored, but Jonah’s finger is still bandaged. Dexter pressures a fearful Jonah to help him stop Arthur from “doing something really wrong” by looking through Arthur’s desk, journals, and computer. Just then, Sally and Rebecca arrive home and Dexter disappears.

Scott wakes up in an underground bomb shelter furnished with bunk beds, a table, and shelves. Arthur is setting up a toy train railroad on the floor. When he finishes, Arthur watches it with childish glee, making sound effects as it loops around the track. Terrified, Scott retreats into the bottom bunk. He doesn’t understand why Arthur called him “Arthur.”

Back at home, Dexter is thinking that Arthur’s ritual was born in the past, like his own. He searches online for missing boys and discovers that five days before a bathtub murder, a ten-year-old boy always disappeared.

Dexter suspects that a bathtub victim represents Arthur’s sister; a jumper represents his mother; a bludgeoned man represents his father; and the boy represents Arthur himself, since he was ten years old when his sister died. Now he realizes that Arthur leaves behind four victims, not three. Missing children weren’t reported as homicides, so Lundy misread the pattern.

In the fallout shelter, Arthur is still playing with the toy train. Scott is hungry, but Arthur wants him to put on a pair of cowboy pajamas. Scott, though, refuses to comply. Arthur, holding plastic models of a man and woman, crouches next to him and says, “Don’t you understand? Father drinks and mother pays the price. I’m just trying to protect you, Arthur.” Scott angrily insists that his name is Scott. Arthur calmly states, “Very well.” Then he walks up the stairs; opens a trap door which lets in the sunshine; and closes it behind him.

After collecting a stack of flyers from Scott’s father, Dexter begins a solo search. He concludes that the Four Walls build site is a perfect place to bury a kid, and it may be where Scott is being held captive.

Donned in his kill outfit, Dexter is pacing through a house under construction, but finds nothing. Jonah calls and Dexter has him check his father’s computer’s search history. He finds school stuff, Bible stuff, a hardware store, a real estate agency, and the local paper. Dexter asks about the real estate agency, and Jonah says it’s a list of homes for sale. Because “Kyle Butler” doesn’t have email, Dexter instructs Jonah to fax the list to a Kinko’s. Jonah asks Dexter how he can see Arthur for what he really is, and Dexter only says that they “have a few things in common.”

Ominously, Arthur is loading bags of cement mix into the back of his van. Unexpectedly, Christine calls and insists that she really needs to see him. Arthur brushes her off, saying they only meet twice a year because he has a full life, and his family needs him. On the verge of tears, Christine pleads, “I’m your family too. I need you. More than they do.” Unmoved, Arthur tells her it will have to wait and hangs up, Christine breathes, “I think I’m in trouble,” and starts to cry.

Arthur re-enters the bomb shelter carrying a tray of burgers, fries, and sodas. He kicks the dust off his shoes and sits down. Scott asks if he can go home. “In due time, Arthur,” says Arthur, as he plays a 1950s-era song on an ancient record player. He tells a very hungry Scott that he can eat after he puts on his pajamas. He then takes a big bite out of a burger, remarking that it’s delicious. This wears down Scott’s resistance and he slips on the pajamas over his t-shirt and shorts.

Dexter spends the evening checking houses on Jonah’s list, but cannot find Scott.

In the fallout shelter, the model train is still looping around its miniature track. Scott asks why he can’t go home, but Arthur ignores him. In frustration, Scott kicks the train off the track. Just then, the song “Venus” starts playing on the record player. As Arthur softly sings along, he begins to cry. He says it was his sister Vera’s favorite song, and repeats over and over that it wasn't his fault that she died. Scott tells Arthur that he’s sorry about his sister, and that it’s okay to call him “Arthur” if it makes him feel better. Scott offers to play with the trains a little longer, adding that Arthur can take him home afterward. Apparently softened, Arthur says, “You’re a dear boy, Arthur. So innocent. Kind-hearted. Promise me you’ll always stay that way.” “Sure,” Scott answers. Then Arthur takes a small plastic cup of vanilla ice cream from a freezer, and secretly mixes in a capsule of white powder. Arthur tells Scott that once he’s finished, he’ll let him go free. Scott smiles and begins to eat the ice cream.

In the backyard of an empty house, Dexter discovers an old, underground bomb shelter. When he climbs down the stairs, he realizes that it’s Arthur’s hiding place. The model train is still set up on the floor and the record player is also there. Dexter notices the empty ice cream cup and is annoyed that he just missed them.

In a parking garage, Arthur is meeting with his eldest daughter, Christine. She reveals that, when she was five years old, she saw him kill a woman in a bathtub after she didn’t wait in the car. For years, she thought it was a dream until it happened again in the same house thirty years later. Arthur tries to convince her that it was a dream but Christine pulls out postcards he had sent her from places where a woman was murdered in a bathtub.

She then tells Arthur that she protected him by murdering Frank Lundy because he was getting too close. After she saw them bump into each other at the plaza, she shot Lundy and made it look like the Vacation Murderers.

However, she’s worried because the police are starting to ask questions. Appalled, Arthur turns away, but then turns back with a smile, and gently says, “You put yourself at risk for me.” Sobbing, Christine promises to do anything for him. He kisses her on the forehead, hugs her, and tells her to go home. He pledges to come over that night and they’ll figure it out. After he gets into his van, he waits until she’s gone before he pounds the steering wheel and screams, “Stupid fucking cunt!”

Still in the bomb shelter, Dexter notices the dust on the floor where Arthur kicked it off his shoes. He drips a little water on the spot and it turns into wet cement. He realizes that Arthur encases the boys to preserve their innocence and rushes back to the Four Walls site.

Dexter catches Arthur zipping Scott into a bag next to a pit of wet cement, “Burying a child in cement. That’s not very Christian,” Dexter remarks. Arthur forbids him to come any closer and insists that he needs to do this. As the bag sinks, the two men begin to battle. Dexter lands a blow with a shovel to Arthur’s head, and he falls to the ground. Dexter quickly pulls Scott out of the cement, finding him unconscious, but alive. Arthur, though, has escaped.

Christine is pacing in her apartment when there’s a knock on the door. She reacts with relief, thinking that it’s her father. Instead, it’s Angel, Debra, Quinn, and a uniformed police officer. They have arrived to take her to the police station.

At the station, Christine Hill is under interrogation by Angel Batista as Debra, Quinn, and Dexter watch on monitors. Christine insists her mother became accidentally pregnant, and she never met her father. Angel, Debra, and Dexter think she’s lying. To have time to kill Arthur, Dexter decides to frame someone else.

Arthur tries calling Christine from his hotel room, but there’s no answer. Turning his attention to the TV, he watches a news report about Scott Smith who is now safely back at home. However, the police don’t know who abducted Scott. “Interesting,” Arthur remarks. He then calls Dexter to ask why he didn’t turn him in for trying to immerse a kidnapped boy in cement. Dexter, improvising, demands $50,000 or he will spread the word that Arthur is a pedophile, which Arthur vehemently denies. Dexter gives Arthur 24 hours to get the money, but Arthur says he can’t because he’s not in Miami. This is clearly a lie as he then takes out a Greater Miami phone book. After hanging up, Arthur searches for “Kyle Butler” in the phone book, finding two names.

Arthur is breaking into a house when the owner returns. Outraged, the young man assumes Arthur is a robber. Chuckling, Arthur claims that he thought it was a friend’s house. When the man threatens to call the cops, Arthur glares at him.

Later, Dexter works the crime scene where the young man is lying on the floor in a pool of blood, with a swollen eye. It’s determined that the victim was choked and had his head smashed against the floor multiple times. Suddenly, Dexter overhears a neighbor mention the victim’s name -- Kyle Butler. He realizes that Arthur is in Miami and looking for him.

Angel and Debra search Christine's apartment where they find packets of postcards under her bed. They’re signed “Love, Daddy” and were sent from the cities of Trinity killings. Debra says it gives them something to “make the bitch talk.”

When another Kyle Butler answers his door, Dexter jabs him in the neck with a syringe of M99. He drags Kyle into the apartment and waits for Arthur to arrive. When he spots Arthur through the window, he stands against the wall, holding his syringe. The door swings open and Arthur is silhouetted in the frame. Suddenly, the door closes, and he’s gone. Dexter realizes what warned Arthur away when he sees Christmas card photos of Kyle and his dog placed by the door.

Angel shows Christine the postcards they found in her apartment and she claims to have never seen them before.

Curious as to why Christine has failed to answer her phone, Arthur swings by her apartment. When he sees the police tape on her door, he walks on by.

Dexter breaks into Arthur’s house and collects items with his DNA to plant in Stan Beaudry’s shack. “Harry” warns Dexter that he’s taken on too many roles: blood tech; husband; father, serial killer; and Kyle Butler, extortionist.

Debra takes a crack at interrogating Christine but it doesn’t go well. Afterward, she, Angel, and Quinn decide to let Christine go, in the hope that she will lead them straight to Trinity.

Dexter heads out to kill Stan Beaudry and set him up as Trinity. While he’s driving, Arthur calls, accusing “Kyle” of lying to him. Dexter retorts that being a liar isn’t as bad as being a pedophile, which enrages Arthur. Dexter again demands fifty thousand and Arthur says he needs one more day.

Christine is back in her apartment and borrows a neighbor’s cell phone to call her father. However, he knows she’s been at the police station and orders her not to call him again. She pleads, “Daddy, I just…” but he hangs up on her.

The next day, Arthur watches Angel on TV as he announces that Stan Beaudry’s truck has been found and it’s yielded evidence pertinent to the Trinity killings. Puzzled, Arthur repeats Beaudry’s name. Christine again phones, distressed that she’s in trouble for trying to protect him. Arthur calls her a stupid girl who’s always gotten in the way. Christine says she loves him, but he remains silent. Christine begs Arthur to meet her, but he replies that she’s on her own. Even worse, he tells her that he’s sorry she was ever born, and states, “Do not call me again. Ever.” Christine, shaking, can hardly breathe from the shock.

While at the Beaudry crime scene, Dexter receives a call from Arthur, who claims he’s rounded up the fifty grand. They bicker over a drop location and settle on a marina entrance. Dexter recognizes the music in the background and realizes that Arthur is at the arcade where he abducted Scott Smith. He thinks Arthur is stalking another little boy, and takes off to catch him in the act.

After a call from Christine, Debra and Quinn rush to her apartment, believing that she wishes to confess. Only Debra enters and she tells Christine that they know her father’s name is Stan Beaudry. “Wow,” Christine utters, though she doesn’t confirm or deny it. For a few minutes, Christine talks about how futile it was to try and make her father love her. She finally confesses to shooting Debra and Lundy, and asks if Debra can forgive her. “Are you kidding me?” Debra answers in disbelief, adding that she’s there to do her job, and will not forgive her. Suddenly, Christine pulls out a gun from under a sofa cushion, places it under her chin, and pulls the trigger. Quinn hears the shot and races upstairs to find Christine in a pool of blood with the gun still in her hand. Debra is distraught.

Dexter is at the arcade searching for Arthur, but unable to find him. A distressed Debra calls Dexter, saying she needs to see him. To be a good brother, Dexter heads back to the station, unaware that Arthur is following him.

From the police parking lot, Arthur watches Dexter enter the station. He strolls inside and learns from the desk officer that there isn’t a Kyle Butler working there. “My mistake,” he says cheerfully. Arthur then meanders over to an old lady, lifts the visitor’s pass from her purse, and casually walks through security.

As he passes a trophy case, Arthur spots a photo of Dexter with his bowling team, labeled “Miami Metro Homicide Bowling Team.” Upon arrival at the floor of the homicide department, the elevator pings and the doors open, revealing Arthur.

Arthur glances around and enters the room with the Trinity whiteboards. He surveys the photos of his victims’ with bemusement. Verifying that Stan Beaudry is the main suspect, he remarks, “Why, Mr. Beaudry, you’ve done me a kindness.” Next, Arthur continues on into the main office area. To his horror, Dexter notices him through the glass -- and Arthur notices him. Dexter whispers, “No,” and hurries out of his lab. They walk toward each other, staring the whole way. Dexter stops in front of him, looking vulnerable. Arthur calmly looks down at his laminate and says, “Hello, Dexter Morgan.”

Arthur and Dexter are standing face to face in the Homicide department. Dexter silently berates himself for letting Arthur find out his name and occupation. Arthur mocks Dexter for trying to “extort money from the Trinity Killer.” After a few threats, he tells Dexter that he’s “not very good at vigilante-ism,” and walks unconcerned out of the police station.

Dexter hurries out to the parking lot where he confronts an angry Quinn and throws him to the ground. He then jumps into his car and peels out to follow Arthur’s van. While Dexter’s weaving through traffic, Rita distracts him with a phone call and he clips a driver’s side mirror, but he keeps going.

Dexter tails Arthur to a parking garage and watches him enter a bank. When Arthur returns with a fat manila envelope, Dexter sedates him and shoves him into the van. The envelope contains a large amount of cash from Arthur closing his accounts, about to skip town and leave his family destitute.

Just then, Dexter notices two deputies and an angry driver outside the garage. He quickly hides the envelope above a light over Arthur’s van and approaches the group. When Dexter loses his temper and smashes the driver’s phone, he’s arrested.

After a few hours, Dexter is released and picked up by Rita. Upon returning to the van where he left an unconscious Arthur, Dexter finds an empty space.

Enraged, Arthur returns home to demand his fearful family’s cash and jewelry, vowing revenge on the person who stole from him.

While searching online, Arthur finds an address for “D. Morgan” but when he breaks into the apartment that night, he learns that Debra Morgan lives there. Meanwhile, Dexter persuades Rita to fly to the Keys without him, promising to meet her there.

The next morning, Dexter sends Rita and Harrison off to the airport in a cab. Immediately, he heads to the Mitchells’ house, only to be told by Sally that Arthur was gone by morning. While he’s still there, Dexter is caught up in a S.W.A.T. raid in which Arthur’s family is taken into custody. Note: During the time of the raid, Rita returns home for her forgotten I.D. and arranges a later flight. This is when she is murdered, according to the FBI in "Hello, Bandit."

As Dexter looks around Arthur’s garage, he remembers the damaged Mustang. He looks again inside Arthur’s wallet and finds an invoice from a body shop where the car is likely being repaired.

Arthur picks up his vehicle and drives off with a smile on his face, feeling like he is getting away with murder. However, Dexter manages to sabotage Arthur's car by removing the oil cap. When Arthur's car breaks down, Dexter ambushes him and takes him to the fallout shelter.

Arthur wakes up immobilized by plastic wrap, surrounded by photos of his victims, with Dexter perched nearby watching him. He realizes that Dexter is a killer, not an extortionist. When Arthur states that God led Dexter to him, Dexter replies, “Hardly.”

When Dexter triumphantly collects a blood slide, Arthur is disgusted and says he never took pride in his killings.

Dexter accuses Arthur of being a special kind of monster who destroyed his own family but Arthur blurts out that he gave them everything. Dexter retorts that he took everything -- their future, dignity, and hope. When Arthur is told that Christine even killed herself, he is momentarily shocked, but then calls her “weak.” Dexter chides himself for thinking he could ever learn something from Arthur.

Arthur asks if he thinks that he’s better than him, and Dexter agrees that he’s not, though he wants to be. Arthur says he also wanted to be different and spent years praying, finally, to be stopped.

When Dexter insists that he’s good for his family, Arthur chuckles and likens him to a child. He declares that it’s all God’s plan and advises Dexter to accept it. Dexter, though, states that nothing is inevitable, to which Arthur remarks, “It’s already over.” Dexter is baffled by the statement, not realizing that Arthur had earlier killed Rita, thus his ambition to become a good husband and father would not be fulfilled.

In his final moments, Arthur asks Dexter to turn on his toy train. Dexter obliges and also plays Vera’s favorite song, for which Arthur thanks him. Then Dexter holds a framing hammer over Arthur’s head and turns it so the claw side is down. Arthur bravely lifts his chin, and Dexter strikes. Arthur’s dismembered body is dumped in the Gulf Stream.

Dexter returns home to find Rita bled out in the bathtub. Nearby, a crying Harrison is sitting in her blood.


Arthur apparently escaped, so the FBI continued to search for him. His family entered the Witness Protection Program and moved to Nebraska.

The only ones who find out that Dexter killed Arthur are Jonah Mitchell, Debra Morgan, and Isaak Sirko, with Harrison learning the truth years later.

Dexter feels responsible for Rita’s death and decides that his family would be better off without him. He takes off on his boat, only to impulsively kill a man who insults Rita. After releasing his rage and grief, Dexter returns for Rita’s funeral.

Looking for a sense of purpose, Dexter targets Boyd Fowler after finding blood inside a moving van.

Dexter encounters Lumen Pierce, who was raped and tortured by the Barrel Girl Gang. He attempts to redeem himself by aiding Lumen in her quest for vengeance.

Arthur's wife and daughter are found murdered in Kearney, Nebraska, apparently by Arthur. Jonah is the only surviving family member. Dexter, aware that Arthur is dead, heads to Nebraska to find out if Jonah has followed in his father’s footsteps. During a confrontation with Jonah, Dexter learns that Rebecca committed suicide due to abuse by their mother, after which Jonah beat their mother to death. Jonah expresses remorse, so Dexter doesn’t kill him.

Several years after Arthur's disappearance, Molly Park, a true crime podcaster from Los Angeles, covers the story of the Trinity Killer in an episode of her podcast. A now teenage Harrison, having recently reunited with Dexter in Iron Lake, listens to the podcast alone in the school gymnasium and grows unstable hearing the details of his mother's death. Soon after, a lockdown occurs at the high school, and Dexter is notified that Harrison was involved in an injury. Arriving at the school, Dexter confronts a wounded Harrison and the police. Harrison states that his friend, Ethan, had asked for his help in murdering several of their classmates, to which he denied, and was subsequently attacked with a knife. Harrison, with a minor stab wound in the abdomen, says he slashed Ethan's leg in an act of self defense, potentially to mimic Trinity cutting Rita's femoral artery. Later, suspecting that Harrison may be lying, Dexter finds a straight-edged razor identical to the one Trinity committed his bath tub murders with. He now realizes that his son has a Dark Passenger as well.

After attacking a group of rival school students with his straight-edged razor, Harrison is stopped by Dexter. He accuses Dexter of thinking he is a 'psycho' and that is the reason he left him. He then admits to him that he had had nightmares of his mother dying when he was young, but only realized they were true after hearing Molly's podcast about the gruesome event. In a flashback, Arthur is seen climbing out of the bathtub after murdering Rita, then approaching a crying infant Harrison, gently telling him, "Daddy will be home soon."

Following Dexter's confession to Harrison that he has violent tendencies identical to his due to him also witnessing his own mother's death, Harrison explains his rage toward Trinity, and confesses that he has fantasized of finding and killing him with his own razor. Later, in Kurt's bunker, the two discover Molly's corpse, setting off Harrison and leading him to an epiphany; Dexter murdered Wiggles, thus stopping his reign of terror. Dexter confirms that he did, and reveals to him that he killed Arthur as well, though he lies and claims it was in revenge for Rita's death, rather than admitting that he had not known she had died until after he killed Arthur. Harrison claims that Kurt must die too.


  • "Camouflage is nature’s craftiest trick.” ~Dexter, referring to Arthur ("If I Had a Hammer")
  • "Hello, Dexter Morgan." - Arthur introducing himself to Dexter ("Hello, Dexter Morgan")
  • "I couldn’t care less about your life. Or death. Unless you get in my way." - Arthur to Dexter ("The Getaway")
  • “If I were you, I'd give up vigilante-Ism. You're not very good at it.” - Arthur to Dexter ("The Getaway")
  • “You can't control the demon inside of you any more than I can control mine.” - Arthur to Dexter ("The Getaway")
  • “So what's the alternative, Arthur? Leave? Disappear? Fake my own death and start over again?” - Dexter to Arthur, who replies, “No. You'll still be you.” ("The Getaway")

Related Pages


  • The Trinity Killer has been polled by viewers as the ultimate antagonist in the series, despite his objectionable methods of murder. His popularity might be due to actor John Lithgow's superb portrayal of the killer, which earned him a Golden Globe award and an Emmy award.
  • The name of Trinity's character was incorrectly listed in IMDb as Walter Simmons (rather than Arthur Mitchell).
  • Arthur's wife's name is Sally, which was the name of the sister of John Lithgow's character in 3rd Rock from the Sun.
  • Both John Lithgow (Arthur) and Julie Benz (Rita) have each appeared in Sylvester Stallone's movies. Lithgow played the main antagonist in Cliffhanger, while Benz appeared in Rambo, playing a damsel in distress.
  • It is speculated that Trinity's character was partially based on Dennis Rader, the BTK (Bind, Torture, Kill) Killer. Both held prominent positions in their churches; both had a family; and both followed a specific routine. Trinity's process could be considered a more drawn-out version of BTK's murders, with the cement burials being the binding, the bathtub kill being the torture, and the last two being the kill.
  • He introduced himself to Tarla Grant as Alan. It could be a reference of Alan Grant, the main protagonist of Jurassic Park movie.
  • Arthur's first name is the same as the middle name of his actor, John Lithgow.

Theme Music

Introducing Trinity
First theme music for Trinity
Trouble with the audio sample?

Arthur has two unique theme songs that are both available on the Dexter Season 4 Soundtrack, named "Introducing Trinity" and "The Trinity Suite." Each of these themes represents the personality of Trinity. He's a survivor that has lasted for over thirty years as a serial killer, and it depicts the fact that he is a man with a dark nature. His theme is used in different versions in Season Seven and in Season Eight.

His theme music is later used in Nebraska when Debra tells Dexter about the murder of Trinity's wife and daughter, and when Jonah walks towards Dexter; in Season Seven for Ray Speltzer; then twice in Season Eight, the first time a short version when Dexter stabs Andrew Briggs in the Pink Motel (Fort Lauderdale), and the last time when Dexter is sneaking aboard the Reverie yacht and finds Miles Castner's dead body with Hannah McKay who had just killed him.


  • Both of Arthur's daughters committed suicide - Christine Hill and Rebecca Mitchell.
  • Arthur was the only main antagonist to be killed by Dexter in a full ritual. He was wrapped in plastic in a kill room, surrounded by photos of his victims. After his blood was taken, he was dismembered, and dumped in the Gulf Stream. Afterward, Dexter placed his blood slide inside his (second) slide box.
  • Interestingly, Arthur was the first main antagonist that Dexter dumped in the Gulf Stream.
  • Arthur was the second Main Antagonist to kill a main character (with his final victim being Rita Morgan). In Season Two, Lila West killed a main character - Sergeant James Doakes.
  • Arthur was the oldest main antagonist as Professor James Gellar was technically not the main antagonist of Season Six, despite being age sixty-five at the time of his death. Walter Kenney was the oldest victim overall, being killed at age 73.
  • Arthur was the first antagonist to substantially affect Dexter's life (since he killed Rita, and Dexter grieved for her throughout Season Five). The second to do so was Oliver Saxon in Season Eight (since he killed Dexter's protégé Zach Hamilton; killed Evelyn Vogel who made the Code; and shot Debra, which led to her stroke and Dexter mercifully killing her.
  • Both Mitchell and Saxon took the life of someone Dexter cared about after he chose to spare them, when he had the opportunity to kill them. (In Mitchell's case, Dexter saved him from falling off a roof to his death; in Saxon's case, Dexter left him tied up when he could have killed him, and Saxon escaped his bindings).
  • Arthur was the second person who found out that Dexter was using an alias around him, and discovered his real name; the first was Zoey Kruger.
  • Arthur was the second main antagonist to be married (the first being Miguel Prado), and the first (and only) one to have children. That said, it is unknown whether or not Stan Liddy was ever married or had children, as he was in his late 50s and very little is known about his past.
  • Arthur was the first main antagonist of the series who was not only present in all episodes of the season, but was also a threat throughout.
    • Brian Moser while being the central threat throughout Season One, did not appear in all of its episodes.
    • Lila West was absent for Season Two's first two episodes.
    • Miguel Prado, while appearing in all episodes of Season Three, was only shown as a corpse in that season's finale, thus not a threat then.
    • Jordan Chase did not appear until halfway through Season Five.
    • Travis Marshall was a protagonist for a majority of Season Six, only to be revealed as the main antagonist (to even himself) near the end.
    • Isaak Sirko died nine episodes into Season Seven, dying as a protagonist rather than an antagonist.
    • Maria LaGuerta was a main protagonist for the first six seasons, but became a main antagonist in Season Seven after Isaak's death (though not linked).