Dexter undertakes to teach Miguel Prado the Code, but doesn't realize he's whetting his thirst for blood; Debra is one step closer to finding the Skinner; Quinn reveals a secret about C.I. Anton Briggs.
Miguel is in Dexter's Apartment and they're enjoying pizza and beer. After Miguel turns the television to ESPN, he hurries over to Dexter's laptop but must wait for Dexter to enter a password. Once online, Miguel suggests a victim to Dexter, former football player Billy Fleeter, a debt enforcer who kills to pay off his gambling debts. Miguel asks Dexter to teach him how to murder Fleeter, but Dexter is hesitant.
As Dexter is making waffles for Cody and Astor, an unsmiling Rita enters the kitchen. She accuses them of making a mess while she's getting ready to start her new job. Her additional grievances include the length of Cody's hair, the marching music that Dexter listens to in his car, the empty orange juice carton, and having to plan a wedding by herself. Dexter silently blames her moodiness on her pregnancy hormones and counts the months until she delivers the baby.
Debra stays overnight in Anton's apartment, but must take a cold shower in the morning because there is no hot water. Before she leaves for work, Debra opens a cereal box and unexpectedly finds a bag of weed inside. She puts it back and doesn't say anything to Anton for the time being.
The homicide department interviews tree trimmers while Dexter researches Billy Fleeter on his computer. George King, the tree trimmer who called in Javier Garza's body, is questioned by Debra. He's polite and respectful and agrees to provide a list of his employees.
Quinn notices Angel and Barbara kissing and teases him that she'll now be watching his every move to see if he's relationship material.
Maria asks Angel to be her date to a police charity event the next night. Angel thanks her for the invite but says that he'll be unavailable. She understands and says, "Good for you."
Miguel and Dexter head to the Oceanfront Casino where Fleeter spends much of his time. Dexter tells Miguel they're only going to watch and learn his routine. While Fleeter plays blackjack, they pretend to play the slot machines. Dexter accidentally mentions the Code and Miguel is curious. Only offering a partial explanation, Dexter says it's a set of rules designed to avoid being caught.
Debra asks Quinn about Anton's previous drug charges and he says vaguely that the info can be found on file. However, when Debra calls Anton to get his C.I. number, he doesn't know what she is talking about. She explains that it's a number on his paychecks, but Anton says that Quinn always pays him in cash.
While Maria and Ellen are on a coffee break, Ellen gripes that Miguel is going out of his way to make her job harder. Maria asks her to accompany her to the police charity and Ellen says she'd love to go.
King is again questioned by Debra and Quinn and he deflects attention to Mario Astorga, his employee. When King reveals that Mario killed a man with a knife in Nicaragua, Mario comes under suspicion as The Skinner.
Dexter is still deciding whether to help Miguel move forward with killing Fleeter.
After Rita hears a love song, she calls Dexter and grumbles that he hasn't bought the wedding bands yet.
Debra half-jokingly threatens to hurt Quinn when he calls Dexter a dweeb.
Debra confronts Quinn about Anton's C.I. status and he admits that Anton was never officially a C.I. He says that he never filed an arrest report in order to save on paperwork. Angry that Quinn is stringing Anton along, Debra mentions that Anton could file a lawsuit. Quinn suddenly realizes that Debra is sleeping with Anton and tells her that it's a "bonehead mistake." Tempers flare even more when Debra accuses Quinn of being responsible for a dead cop, according to Yuki Amado.
Dexter and Miguel break into Fleeter's house and locate the murder weapon -- a baseball bat. However, Dexter wants additional evidence proving that Fleeter has the incentive to kill again. He finds it in Fleeter's ledger where he records each of his bets and how much he owes.
An irritable Rita is writing addresses on wedding invitations while complaining to Sylvia about Dexter's lack of help with the upcoming wedding.
Debra informs Anton that he is no longer a C.I. but she doesn't reveal Quinn's deception. She pretends the reason is a clerical error. Since The Skinner is still at-large, she wants Anton to have a protective detail, but he won't allow it.
Dexter takes Miguel shopping for the supplies they will need. When Miguel begins suggesting the wrong items, Dexter tells him that he'll put together a "starter kit" for him.
Dexter and Miguel set up a kill room at the casino in an unused storeroom.
After Maria and Ellen attend the boring police charity event, they want to have fun and go to a bar. Ellen begins flirting with Toby, the bartender, and he's quite friendly in return.
With everything prepared, Dexter and Miguel visit the casino for a second time. They sit at the bar near Fleeter who is drinking and watching a basketball game. Miguel is dressed, as Dexter describes it, like the Unabomber. Fleeter's team loses and he leaves in a bad temper. They begin to follow Fleeter but on their way out, Miguel is recognized by a stranger. This results in Dexter calling off the planned kill since Miguel has been seen in the same place with the proposed victim.
Anton isn't answering Debra's calls and she's worried that he's lost interest in her.
Dexter reads in the news about another murder, apparently by Fleeter.
Debra helps Dexter at a jewelry store as he picks out wedding bands. When she advises him that they should match the engagement ring, he says that he never bought one because Rita didn't want one. Debra berates Dexter for being an idiot and orders him to buy a large diamond ring for Rita. While there, Debra asks his opinion on her love life, though hypothetically. It's not what she wants to hear, however, and she angrily leaves the store.
Debra and Quinn are on a stake-out at Bayfront Park where Mario Astorga is expected to work. While they're waiting, Debra asks Quinn if it's true that a cop died because of him. Quinn explains that his partner in Narcotics, Detective Stewart, developed a crystal meth problem... but he didn't report it. Unfortunately, Stewart made a bad judgment call during a bust and shot an unarmed coke dealer which left him paralyzed. Stewart then went on a bender and committed suicide by shooting himself.
Mario shows up at the park but when he spots Quinn and Debra, he flees. Quinn, though, runs after Mario and tackles him. They bring him back to the station but he won't say a word.
Due to the workload, Angel must break a date with Barbara and leaves a message with an awkward apology.
During a meeting on a pier, Miguel tries to persuade Dexter to go ahead with the kill. Dexter stresses the importance of the Code after Miguel says it's a "straight jacket." He asks Dexter how many people he's killed, but Dexter doesn't answer. Dexter finally agrees to go ahead with the kill after Miguel begs Dexter to help him let out his own darkness, adding that he had beat his abusive father and it was one of the most satisfying moments of his life.
During interrogation, Mario admits to Debra and Quinn that he stabbed a man in Nicaragua but it was for good cause, and the man survived. Quinn threatens Mario with deportation, but he remains defiant until George King is mentioned. Immediately, he panics and begs them to send him back to Nicaragua, with or without his family. Suspicion now centers on King
Barbara shows up at Angel's desk with dinner for him. He's relieved when she says that she laughed at his voicemail message.
Anton still isn't answering his phone and Debra finds out that he didn't show up for a band performance.
Dexter and Miguel lie in wait inside Fleeter's house. After Dexter injects him with M99 at his house, they take Fleeter to the casino storeroom. Miguel stabs and kills Fleeter, stating afterwards that he feels "fantastic." Dexter insists on disposing of the body by himself because leaving no trace is his area of expertise. While cleaning up the crime scene, Dexter has thoughts of Harry telling him that sharing the Code was a mistake and Dexter is now responsible for Miguel's actions.
Deeply worried about Anton, Debra goes to his apartment but he's not home. When she notices that the trees nearby have been trimmed, she realizes that Anton has been taken by The Skinner.
Dexter surprises Rita with the engagement ring and she melts with joy. She apologizes for her recent moodiness, saying, “It's like I have this monster living inside of me, and I don't know how to control it.” Dexter replies, “Maybe I can help you out with that one.”
Miguel makes an unannounced visit to Ellen's house. She opens the door, expecting to see Toby, the bartender.
- It's said that everything is connected to everything. The butterfly effect. You drop a pebble into a pond, and the ripples radiate outward, touching and effecting everything. Until finally a fish grows arms and legs and crawls out of the water. And picks up a rock and smashes the next two fish over the head. And we have the first serial killer. - Dexter [voice-over]
- “You ever drop a quart of milk? Watch it spread over the whole kitchen floor, the mess it makes? There's six quarts of blood in the human body. This isn't gonna be pretty.” - Dexter to Miguel
- “Dex, after fourteen years of filing briefs, trying cases, and dealing with bullshit… this is all gonna look nice and neat in comparison.” - Miguel to Dexter (while setting up a kill room)
- Casino scenes take place at Hollywood Park Casino in Inglewood, CA.
- Anton Briggs' Apartment
- Billy Fleeter's House
- Code of Harry
- Detective Stewart
- Dexter's Apartment
- Ellen Wolf's House
- Jewelry Store
- Kill Room
- Kill Tools
- Oceanfront Casino
- Rita Bennett's House
- Skinner Case
- West Marine
- Yuki Amado