Dexter finds himself unable to kill again after the harrowing conclusion to the Ice Truck Killer case, and strays from his personal code with disastrous results; Debra returns to work but may not be ready.

Dexter remains on the trail of a dangerous new victim, while the traumatized Debra loses control on the job and a high-profile FBI agent arrives in Miami to investigate a newly discovered serial killer.

Dexter's inability to deceive has him pursuing a slick liar as his next victim, while Rita believes he's concealing a drug problem and forces him into a 12-step program where he meets Lila, a seductive new woman.

Rita finds herself threatened by Dexter's sexy new NA sponsor Lila, and stressed by a visit from her estranged mother, while Dexter tries to throw the dogged FBI Agent Lundy off his bloody trail.

A new copycat killer openly mimics and claims to be inspired by the "Bay Harbor Butcher," driving the annoyed Dexter into the arms of Lila, a development that could spell the end of his relationship with Rita.

A written manifesto from the "Bay Harbor Butcher" sends the task force in charge of capturing him into chaos, which is part of Dexter's plan for keeping Lundy off his trail.

Dexter decides that Lila is becoming too attached, decides "recovery" isn't working for him, and pays another visit to his mother's killer; Debra and Lundy find a clue that points to the "Bay Harbor Butcher" being right under their noses.

Dexter tries to distance himself from Lila, but discovers she is unwilling to let go of their relationship; Lundy's manhunt makes Dexter nervous as he tries to stay one step ahead - but it's Dexter's worst enemy that learns his secret.

Dexter's world comes crumbling down when Doakes tracks him to the scene of his latest kill and reveals a devastating secret about Harry; the Miami Metro PD closes in on the "Bay Harbor Butcher."

Dexter dodges bullets both figurative and real as he is forced to decide the fates of those he cares about most. Lila attempts to blackmail Dexter and makes a startling discovery.

Special Agent Lundy and the FBI finally settle the case of the Bay Harbor Butcher, but the heat's not entirely off Dexter as the flames literally close in.