The next potential killer on Vogel's list is A.J. Yates, who was institutionalized at 15. Vogel tried to channel his hostilities much as she did with Dexter but was unable to do so. When Dexter sees a huge scar on his head, he learns from Vogel that Yates had surgery to remove a brain lesion. He breaks into Yates' house and finds something interesting in the closet. Dexter isn't alone in the house however and it looks he may be their man. He also finds something that affects his relationship with Vogel. Dexter meets a neighbor, Cassie, from the next door apartment. ...

Dexter is convinced that Zack Hamilton killed Norma Rivera but has no proof and takes to following him whenever he can. He's more than a bit surprised to follow him to Dr. Vogel's office. She admits that Zach is a new patient but refuses to talk about his case. Batista is under pressure from Deputy Chief Tom Matthews to make a decision on who to promote to sergeant. When Quinn learns he didn't get the job, he redoubles his effort to solve the Rivera murder. With Dexter tagging along, it becomes obvious - to Dexter at least - that Zack is stalking his next victim, ...