Dexter is caught up in a very personal case that awakens the needs of his Dark Passenger; Debra feels overwhelmed by her new Lieutenant duties, made all the more complicated when she finds out Quinn slept with a witness in the Doomsday case.

Dexter tries to figure out the Doomsday Killers' next victim before it's too late; Debra has a strong reaction to a crime scene, which leads her to the realization that she leans too heavily on her brother.

Dexter tries to bring Debra on board with his new target. While the Ukrainian mob seeks revenge for the killing of one of their own, Quinn grows close to a dancer at their strip club.

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 monitors a young psychopath to see if he is suited for his table. Dexter and Debra finally get back to normal, but are surprised by his ex, Hannah.

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.