In the sixth-season finale, Dexter and Homicide try to stop the Doomsday Killers from committing one final murder, while Debra deals with a new emotional situation.

Dexter develops a macabre scheme to try to apprehend the Doomsday Killers. Meanwhile, Debra and LaGuerta’s battle over the case of the dead call girl intensifies and Debra’s therapist makes a bold and disturbing suggestion

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 is accompanied by a fellow Dark Passenger on a trip to Nebraska to tie up past loose ends. Meanwhile, Debra’s investigation into the Doomsday Murders is complicated by her lieutenant rank.

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.

Gellar and Travis’ latest disturbing tableau has Dexter questioning matters of faith. Meanwhile, Homicide uncovers evidence that the killings are religion-motivated and tries to find the zealot responsible; Debra gives her first official press briefing.

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

Brother Sam, a minister with a criminal history, is brought in by the homicide department to help solve a macabre murder, but Dexter sees him for what he really is—and it’s definitely not a man of God. Elsewhere, Debra’s sudden hero status elicits a pair of surprising proposals

Dexter Morgan attends his 20th high school reunion; Dexter considers his son’s legacy; Debra becomes an unexpected hero.