A troubled young woman who, in a last-ditch effort at getting her life together, takes a job working nights as a security guard at an abandoned luxury apartment building. Stuck with a brusque rent-a-cop as her partner, she tries to not let her mind play tricks on her while she patrols the empty halls. But as the night progresses strange things begin to happen - and she realizes it may not all be in her head.
Desperation drives two nuns to perform an exorcism no nun should attempt. With a possessed child at the mercy of evil and the opposition of the Catholic Church, they take on the dangerous forbidden rituals themselves, putting their immortal souls in grave danger. They must confront the terrifying cost of their sacrilegious actions, but one goal remains: the boy must be saved at all costs.