Dexter is caught up in a very personal case that once again awakens the needs of his Dark Passenger; Debra feels overwhelmed by her new lieutenant duties, made all the more complicated when she finds out Quinn slept with a witness in the Doomsday Killer Case.
Dexter follows Travis in a market place, hoping that he will eventually lead him to Professor James Gellar. However, he receives an urgent call from Debra who tells him that Brother Sam has been shot and is in critical condition. Dexter immediately rushes to the Good Shepherd garage as Travis meets Gellar and purchases a fabric for the "Whore of Babylon" tableau. Travis begs Gellar to give the woman they kidnapped before some painkillers to ease the pain of her broken armm but Gellar refuses, saying that she is a "whore" and deserves it.
Dexter arrives at the scene as the EMTs are rushing Sam to the hospital. Dexter suspects that the shooting was an act of revenge for Julio Benes and one of Julio's men that he attacked before was the culprit. Dexter scrapes some blood from Sam's bat and identifies the man as Leo Hernandez. Dexter contacts Leo's last known address hoping to find a lead to Leo's whereabouts but no such luck. Dexter blames himself for what happened to Sam as he was the one who killed Julio and the Locos gang blamed Sam for Julio's disappearance.
Meanwhile, Debra feels the pressure of being avoided by her friends due to her position as their superior and she barely has time to catch up on the work.
Batista and Quinn unravel Gellar's plan to sacrifice seven people to bring on the end of the world in a manner depicted in his journal. They also discover that three years ago, Gellar did an artistic installation on campus with a female accomplice who Quinn identifies as Carissa Porter. Quinn requests Batista to keep his one night stand with Carissa a secret from Debra.
Meanwhile in Gellar's hideout, as Travis prepares the "mark," he begins to feel sympathy as he hears the kidnapped woman scream in agony due to her broken arm.
Dexter misses his friendship with Brother Sam, since Sam saw his darkness and wanted him to follow the path of light.
Debra reveals to her psychiatrist that she feels that her world has been turned upside down since her promotion to Lieutenant. Her psychiatrist suggests that she should have a party in her new beach house.
Dexter parks by Leo's house to wait for him. However, at the same time, Detective Anderson, having learned of Leo's whereabouts from a junkie, leads a raid at Leo's house which results in Leo's death.
The police deduce that Leo was the culprit. However, Dexter reviews the security footage from Sam's garage found in Leo's house and notices that Eli, Sam's guard dog doesn't act up, something that the dog only did around Sam and Nick.
Elsewhere, Travis begins storing his blood in several jars for an unknown purpose. He brings the woman some food and apologizes to her that he can't give her any painkillers or let her go. Travis later visits his sister Lisa at her school where she teaches elementary students.
Dexter begins to investigate Nick and finds the bullet shot earlier in his apartment (at Brother Sam when he was high). It matches the bullets shot into Sam.
Batista interrogates Carissa regarding her relation with Gellar, but all goes wrong as Debra orders Quinn to join the interrogation. This results in Quinn's affair being exposed and losing Carissa as a key witness that could help solve the Doomsday Killer Case.
Brother Sam regains consciousness but his condition begins to deteriorate. Dexter meets with Sam at his deathbed and is told by him to put his darkness aside, embrace the light, and forgive Nick.
Meanwhile, Debra holds a housewarming party at her beach house but it's interrupted by a drunken Quinn, who brings a date.
As Travis prepares to give the woman the "mark," he instead shows mercy by letting her go.
At the party, Quinn becomes rude towards Jamie and is punched by Batista. Quinn states that Debra never loved him and leaves in a cab.
After receiving word of Sam's death, Dexter is hesitant to agree to Sam's dying wish by just letting Nick go. While thinking it over, he takes Nick to the beach, and reveals that he knows Nick was the shooter. Nick appears nervous and upset, admitting that he needed to shoot Sam to prove himself to the gang. Dexter decides to forgive him and tells Nick that Sam forgives him. Nick insists on seeing Sam only to hear that he passed away that night. At first, Nick seems to be very upset, but he suddenly replaces this with intense joy. This blatantly disrespects Sam's sacrifice for him and disgraces the fact that Dexter chose light over darkness. The rage builds up inside of Dexter and he tackles Nick, drowning him in the same waters where he was baptized.
Immediately after killing Nick, Dexter's darkness represented as Brian Moser appears, clapping his hands, and Dexter slightly smiles.
- Biscayne Bay
- Community Charter School
- Debra's Beach House
- Eli (dog)
- Good Shepherd Auto Repair
- Santa Maria de Loreto