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.
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
While in the midst of hunting down their next victim, Dexter and Lumen are surprised by the return of an unannounced guest. Debra is assigned to the file room, but still manages to uncover new evidence in the Barrel Girl case.
While attending a self-help seminar, Dexter and Lumen vet and stalk a violent killer. Debra gets into some unexpected trouble from the fallout of the Santa Muerte case, forcing Batista to make a difficult decision.
While helping Lumen, Dexter finds himself on a collision course with Debra and the rest of Homicide when he is called to investigate a horrifying crime scene. Meanwhile, the Santa Muerte case leads to a violent standoff between Debra and the Santa Muerte killers.