The episode begins with Dexter cleaning his boat while listening to some advice from Harry. Harry doesn't think Debra will be able to handle who he is long-term. Dexter finds traces of a lot of blood, and is visibly surprised. Masuka has learnt Maria processed a blood slide at a private lab and is freaked-out, as it means he's going to get fired. Debra asks Maria, who tells her she thinks it's possible the Bay Harbor Butcher is still alive, and might still be hunting down innocent victims. Lundy's notes indicate that he doubted Doakes was the real killer. Maria brings her into her secret, your eyes-only investigation. Debra gets into the elevator and begins to panic.
Dexter learns that Louis was the one killed on his boat. Seconds later Debra tells Dexter about the slide with Travis' blood. Maria wants them to speak with everyone who has gone missing since Doakes died and fits the profile of a BHB victim, to find out anything pertinent if they can. Dexter points her three people that he took care of. Only one of them, Phillip Barnes, has family in Miami, so Debra will make sure she gets his name. Dexter tells her Barnes was a wedding photographer who would find and kill single female guests. Debra is upset that Dexter grabbed him at a reception, meaning it's possible he was photographed. Dexter comes home and sees his curtains are open and is immediately on the alert.
It is shown that, Isaac is waiting for him with gun drawn. Dexter goes to his car and calls his machine, pretending to be somebody confirming an appointment with Dexter, in order to mislead Isaac. Isaac hears this, buys into the false premise and heads out. Dexter sees him walk out and recognizes him from the strip club. Dexter calls Isaac and they establish where each other is coming from. Isaac tells him that his plan is to take care of both Dexter and Debra. Dexter meets with Debra and tells him about Isaac and the potential for danger because he killed Viktor. Debra is furious that Dexter found Viktor's fingerprint at the scene of Anderson's death and didn't tell the police, and makes it amply clear how wrong it was of him to do so.
She wants to arrest Isaac before he can do anything untoward, but he tells her that they can't afford Isaac talking, as he would reveals details that would expose them. Dexter's plan is for them to go to a hotel and take special precautions when leaving the station. She makes him promise to never take a case from the department again as she feels what he did was completely wrong. He reluctantly promises, but somehow Debra doesn't seem to trust his answer. Later, while watching the strip club Dexter realizes that Isaac is a boss. Angel calls him with word that Hannah is on her way in and plans to talk them through her spree with Randall and how it related to the belongings Randall's mother brought in.
Hannah fills in the blanks for Angel and Dexter, saying they buried bodies near the hotels where they were killed. When Angel leaves the room Dexter notices that Hannah seems more nostalgic than scared as she plays with a toy. Dexter reads about feud Isaac's organization is having with the Columbians. In the hotel room Dexter and Debra relive childhood memories from a beach vacation. Dexter and Angel wait while another Randall victim is dug up. Angel asks him about the bartender who confessed to Anderson's murder. Hannah and Dexter talk about blood. Maria surprises Debra by meeting her at the Barnes home.
Barnes's son tells the women his father used to beat him and his mother and his life has been better every since Barnes disappeared. He brings them some pictures from the wedding his father had been working when he disappeared. As Maria is looking away, Debra spots Dexter in one of the shots, much to her surprise. She suggests they take them to the station and spend more time on the analysis. The couple Randall killed is dug up. They were kept very well preserved by the shower curtain they were buried in. Dexter begins going through how they were killed out loud, but as he looks at the female victim he realizes she was killed by someone much smaller than Randall.
He doesn't say this out loud and glares at Hannah, who looks concerned at the way Dexter is looking at her. When they're alone Hannah asks Dexter why he stopped; as she suspects there is more to the whole thing than meets the eye. Dexter tells her he knows her story is a lie, pointing out a scar on her hand, which he feels reveals the actual truth. She says the DA gave her immunity from any crime committed with Randall, so she isn’t answerable for it. Dexter spots Isaac nearby. Dexter makes sure not to lose Isaac as he drives to a bar in a part of town frequented by his Columbian enemies. Dexter then walks in, makes reference to Isaac's gang, and then sneaks out a bathroom window, having done his job effectively.
Isaac follows a few moments later, none the wiser. While Debra looks at the wedding photos featuring Dexter, Angel comes in and brings up Anderson's murder. Just then they get a call about a homicide at the Columbian bar. But when they arrive they find only dead Columbians. As it turns out, all by himself, Isaac was able to kill three people. But in the process, Isaac too was cut and some of his blood is found split, at the scene. While Isaac is being stitched up at the club, George spots Quinn with Nadia. He tells Isaac that Quinn used to be on the take. In his car Quinn finds a bag of cash on the seat. He sticks it in the glove and drives off.
Later, Isaac is brought into the station in cuffs, for questioning. He and Dexter come face to face and glare at one another briefly, but reveal nothing. Angel tells Debra he doesn't think Alex the bartender killed Anderson. Alex had no connection to Kaja, meaning somebody put him up to it. Debra basically cuts him off before he can draw too many conclusions, saying that since there is no concrete evidence they can't afford to re-open the investigation. She orders him to "let it go" and he reluctantly agrees, seeing the logic in Debra’s argument. Dexter and Isaac chat through the prison glass. Dexter asks why it's so important that he kills him.
Isaac assures him that he'll get revenge for Viktor, no matter how long it takes. Dexter responds that if Isaac ever finds out who he really is, "you'll regret it". Debra brings Dexter the photo of him taken at the wedding. He thanks her for saving him. She says that her conversation with Angel made her realize she didn't want to be a part of what he does. They have a beer together and once again talk about the vacation, they were discussing earlier. Dexter then burns the photo and Debra walks away. The episode ends at this point.