Season synopsis
Contains spoilers for this season and earlier seasons.
After Brian’s death, Dexter finds himself unable to kill while Doakes watches him and Debra stays with him to recover from the Ice Truck Killer’s attack. Divers then uncover the bags of body parts Dexter dumped offshore, and Miami Metro joins an FBI task force led by Frank Lundy to find the Bay Harbor Butcher. Rita confronts Dexter about framing Paul; when Dexter admits it but offers no convincing explanation, she mistakes his absences for drug use and sends him to Narcotics Anonymous. There he meets Lila Tournay, who becomes his sponsor and lover.
Dexter resumes killing and shifts his dumping ground, but the investigation narrows toward people with police training. He also learns that his mother Laura was a confidential informant for Harry, that Harry had an affair with her, and that Harry later died by suicide. Doakes discovers Dexter’s blood-slide collection, but the task force later finds the slides in Doakes’s car and mistakes him for the Butcher. Doakes flees and follows Dexter to a cabin in the Everglades, where Dexter captures him, admits the truth and keeps him locked in a cell while weighing his options.
Lila uses Dexter’s car GPS to find the cabin. After Doakes tells her who Dexter is, she chooses to protect Dexter and sets off an explosion that kills Doakes. Police find Doakes with the evidence Dexter left behind, close the case and publicly blame him for the murders. Dexter turns against Lila after learning she is dangerous, but she retaliates by kidnapping Astor and Cody and trapping them with Dexter in a fire. Dexter gets the children out alive; Debra abandons her planned departure with Lundy and stays in Miami. Dexter later tracks Lila to Paris and kills her, returning to Rita and the children with his secret still undiscovered.