Dexter Morgan is a Miami-based blood splatter expert who doesn't just solve murders; he commits them too. In fact, he's a serial killer — but he only murders the guilty, so he feels justified with his lifestyle choices. His policewoman sister and his cop co-workers have no idea Dexter lives a double life; however, adoptive father Harry knows his secret, and does, in fact, help Dexter hone his "skills." It's a unique brand of justice for which charming Dexter feels a psychological hunger.
It’s Christmas time, and Debra learns it may be better to receive when she gets a tip from Hannah’s father… one that could lead to incriminating Dexter in a crime. Meanwhile, Dexter discovers that the man behind his mother’s death has been released from prison.
Dexter enlists Dr. Vogel’s help to lure the Brain Surgeon to a location in order to get him on the table. Later, an important person in Dexter’s life is murdered before his eyes.
Dexter investigates a murder that hits close to home. Meanwhile, Dr. Vogel gets the surprise of her life when someone from her past returns.
Dexter is unnerved when Hannah’s father pays him a surprise visit; the Phantom Arsonist’s crimes become more vicious; and Quinn defends Nadia’s honor and finds himself in a volatile situation. Meanwhile; LaGuerta asks a former superior for help on the Bay Harbor Butcher case.
Dexter tracks down his protégé in the belief that he murdered his neighbor. Meanwhile, Dexter tries to help Hannah escape the country.
Dexter hunts down Hannah to figure out why she’s back in Miami. Dexter also takes on a protégé and starts teaching him the Code.
As Dexter scrambles to track down Isaak, a power struggle erupts among the Koshka Brotherhood, which could prove to Dexter’s advantage. Meanwhile, Miami Dade tries to smoke out the Phantom Arsonist.
Dexter monitors a young psychopath to see if he is suited for his table. Dexter and Debra finally get back to normal.
Dr. Vogel gets abducted by the Brain Surgeon, while Dexter and Debra try and rescue her. Masuka finds out he has a daughter.
Fresh out of jail, Isaak renews his pursuit of Dexter while Quinn continues his power struggle with the Koshkas. Dexter tries to keep Debra in the dark about his relationship with Hannah, but a surprise visit from Astor, Cody and Harrison throws a wrench into his plans.
