The episode begins with Dexter talking about feeling trapped with Debra looking over his shoulder 24 hours a day. He mails something to Miami Metro in hopes of getting rid of Louis. Even during the morning briefing Debra is glaring at Dexter, to the point Masuka notices. While attempting to get a DNA sample from a suspect Dexter snaps and starts choking the man. He tells Debra that she is the problem, suppressing his urges won't work. The only way he thinks he can control it is to channel it. Debra thinks eventually this will catch up to both Dexter and Harrison.
Dexter goes back to his regular routine, finding the file of a man named Raymond Speltzer who has been paroled for assault but has probably killed several women. He thinks Speltzer, a cemetery groundskeeper, will kill again if he doesn't stop in. Dexter works out at Speltzer's gym as a way to begin watching him. Dexter wonders if Speltzer could be starting his kill ritual. Debra is watching Dexter like a hawk. Nadia comes to see Quinn and tells him she was wearing a bracelet the night she was killed. There is no mention of the bracelet in the report. He asks her on a date and she offers to cook him dinner. Nadia returns to the club and reports back to George what she saw in the file.
Turn out, the bracelet contains a GPS chip that the organization uses to track its heroin mules. Isaac is also in the office. He instructs Nadia to get close to Quinn and find out what the police know about Viktor. She leaves and Isaac tells George that Viktor was smart enough to take the bracelet off of Kaja. Isaac thinks they should be able to track the bracelet and find Viktor. The package Dexter sent lands on Masuka's desk. It contains the ITK arm, along with a letter to Louis complaining about the quality of the item purchased from him. Masuka is furious Louis had the hand and sold it online and fires him on the spot. Louis glares at Dexter on his way out.
Randall's mother brings Debra some items she hopes will help the police find more information about some of his victims. They are items Randall and his girlfriend Hanna collected on their spree. Among the Randall items Dexter finds things which belonged to a woman named Janice, potentially another victim. The body of the bouncer Isaac killed with the screwdriver has just been found. Dexter tells Debra he won't be coming that night because he'll be working out. Louis comes home to find Jamie watching the video of him having oral sex with the prostitute. It was sent to her anonymously and she is done with him. He tells her Dexter is trying to ruin his life and she thinks he's losing his mind.
Well aware she's been following him, Dexter brings Debra to the bar where he's observing Speltzer. He tells her Speltzer's shaved his head, something he did around the time of his two previous murders. Dexter shows him Speltzer hitting on a woman. He' showing her the reason he does what he does, that he's essentially saving lives. She's not going for it, so Dexter thinks he has to find her more proof. At the cemetery Dexter observes Speltzer spending time inside a private mausoleum. But before he can go inside Debra calls him needing him to work. Isaac brings in an IT guy to locate the tracking device from the bracelet. He's able to track its history following Kaja's death.
It was at Viktor's apartment, the airport, the marina and then eight miles out to sea. Isaac realizes Viktor must be dead and tells the IT to pinpoint the exact marina slip from which his killer would have departed. At the office Dexter tells Debra what he thinks Speltzer is going. An alarm is going off inside his "lizard brain," which tells Dexter the man will kill again. He points out that his brain has helped her catch killers time after time in his role as a spatter expert. She tells him she'll take care of it. Angel and Dexter stop at the strip club and Angel confronts him about Tony. While they talk, Dexter strikes up a conversation with Isaac, who is reading a paper.
They speak in generalities about the fact both of them are looking for something. Next they pay a visit to Hannah, Randall's then-teenage girlfriend who fell for the wrong guy but didn't participate in the crimes. After testifying against Randall, Hannah has turned her life around as a business owner. Dexter takes a DNA sample from her and for a second she seems intrigued by him. Debra asks Maria for help getting a warrant to search for the mausoleum. She says she has a hunch, but that isn't enough for Maria to press the judge. Isaac and a few thugs arrive at Dexter's slip, where Louis is preparing to drill holes in Dexter's boat. Not knowing who they are, Louis initially says the boat is his. But when Isaac threatens to drill into his eyeball Louis tells them who the boat belongs to.
Isaac then shoots Louis in the head. Dexter climbs the fence at the cemetery. Debra has a patrol follow Speltzer, but they leave when he seems to be in for the night by himself and another call comes in. Nadia tells Quinn the truth about her bosses wanting her to get close to him. But she tells him she actually likes him. Quinn's plan is to give her enough info to keep her bosses happy, in exchange for her letting him know what they're up to. She warns him that Isaac's organization is dangerous. The woman who Speltzer was talking to at the bar the other night drops by his place for a drink. Dexter breaks into the mausoleum and finds a shrine featuring the earrings of one of his suspected victims.
Dexter tries to text Debra a picture of the shrine but gets no service. She tries to call him and leaves a message, saying she's going to drop by Speltzer's place. Speltzer and the woman begin talking and it's readily apparent that he's a complete whack job. He starts choking her and says "let's play a game". Debra pulls up at Speltzer's. Dexter locks up the mausoleum and listens to Debra's message about going to Speltzer's house. He sprints to his car. Speltzer has created a type of maze on the second floor of the house, and is chasing the woman through strobe light and heavy metal music while wearing a strange helmet. Hearing screams, Debra shoots out the lock and heads upstairs.
She fights Speltzer, who knocks her gun into some barbed wire. Just before he can grab her Dexter hits him in the head with a two-by-four. They find the woman severely beaten with her earring missing. Speltzer is gone. The woman ends up dying and Speltzer seems gone for good. After some early morning soul-searching Debra goes to see Dexter. She tells him he was right. If she'd listened to him the woman would be alive and Speltzer would be dead. She hates what Dexter does but she "gets it" .She thinks he's a necessary evil. She references his slides and Dexter admits he likes to kill. Debra wants him to move back to his place. Dexter is "finally out of my cage". The episode ends at this point.