Dexter races to identify the Doomsday Killers’ next victim. Meanwhile, Debra’s surprising reaction to a crime scene leads her to wonder if she depends too much on her brother.

Dexter receives help from an unexpected source while hunting the Doomsday Killers and staying one step ahead of Homicide; Debra discovers something new about herself in therapy.

Dexter uses lessons he learned from Brother Sam to follow up on some new leads in the Doomsday investigation; Debra butts heads with Captain LaGuerta over the case of a dead call girl.

Dexter finds himself teamed up with a fellow Dark Passenger when he takes a road trip to Nebraska to tie up some loose ends from the past; Debra deals with the complications of her promotion as she leads the Doomsday investigation.

Dexter’s case turns personal, while Debra’s new duties as a lieutenant leave her feeling overwhelmed. She also discovers Quinn made a professional faux pas

Dexter receives spiritual guidance from his new friend, Brother Sam, while his search for the Doomsday Killers leads him in a new direction. Later, Quinn and Batista visit Prof. Gellar’s former university; and Debra is required to undergo post-shooting therapy.

A serial killer from Dexter’s past makes a shocking reappearance; Debra has problems settling into her new job; and Travis and Gellar contemplate their next move