Dexter considers the nature of faith while stalking the Doomsday Killer, a vicious, deluded, religious fanatic who displays his victims in grisly, Biblical-themed tableaux. Deb gets promoted to lieutenant and reconsiders her relationship with Dexter. Quinn goes on a season-long bender that threatens his partnership with Batista. Masuka hires an intern who is in awe of Dexter.