Dexter enters therapy with a psychiatrist, Dr. Emmett Meridian, who he suspects is a murderer.
Dexter becomes suspicious when he discerns a pattern of recent deaths of powerful women by suicide. He discovers that all the women have consulted the same therapist, Dr. Emmett Meridian, so Dexter visits him under the pseudonym "Sean Ellis." The therapist actually helps Dexter with his intimacy issues, allowing him to have sex with Rita. During his therapy appointment, Dexter notes that the therapist is surreptitiously recording his sessions. At night, Dexter breaks into the therapist's office, erases the video of his session, and reviews the videos of the sessions of the dead women, discovering that the therapist has used both drugs and psychology to induce them to commit suicide. Dexter books another appointment as Sean, confronts and subdues the therapist, and kills him.
Perry confesses that he is not the Ice Truck Killer after he freaks out at the sight of a severed head. Dexter sends the real Ice Truck Killer a message via Craig's List. Dexter's sister, Debra, brings her relationship with the prosthetist, Rudy, into the open. Rudy is revealed as the Ice Truck Killer when he responds to Dexter's message via online and then walks into his freezer of body parts, blood, and sliced Barbie dolls.