When their city is rocked by a series of brutal occult murders, veteran detective John Locke and his young partner Terri Keyes are forced to put aside their differences and follow the trail of evidence to a formerly abandoned asylum, where the new owner Dr Unnseine is conducting his own brand of Nazi-inspired "medical research" on the unwilling inmates. One such inmate, the sexy but deadly Annie Dyer, may hold the key to the murders - and to the doorway to Hell itself - if only Locke and Keyes can stay alive long enough to discover what it is.

Annie Dyer moves into a new apartment and quickly discovers she is not alone; a malevolent spirit repeatedly attempts to seduce her in order to possess her body as a vessel to carry out its vengeful mission.