The film begins with a family of three travelling along a highway. The scene ends with a child screaming, and the male protagonist (Wes Bentley) is seen resting in a bed, in a large room, attached to hospital equipment. The female protagonist (Kate Bosworth) visits him dressed in formal business attire, which is a frequently re-occurring theme in the film.
The male protagonist is show to become suspicious of the female protagonist, who claims to be his wife. When she leaves to conduct errands, the male protagonist explores the house. After leafing through a photo album, he searches the basement where he finds a film projector, medical tools, anatomy charts and books, and a corpse hidden in a cabinet. He confronts the female protagonist when she returns home, who explains that the corpse is her first husband before knocking the man unconscious and drugging him.
The male protagonist wakes up restrained to a bed, his captor being the female protagonist. She administers shock treatment, telling him that he must provide a family for her if he wishes the ordeal to end. When asked why the photo album contains no photographs of the female protagonist of her late husband, the two become involved in a physical confrontation. He attempts to subdue her, but is in turn subdued when hit with a nearby vase. He is restrained, but escapes briefly before being knocked unconscious. A visiting postman is killed by the female protagonist who pushes the body into the basement. A detective assigns an officer to investigate a report regarding the missing visitor, who is a mailman.
While the female protagonist dismembers the postman downstairs, the officer comes to the door. She attempts to gain entry to the premises, and is promptly killed by the female character. It is at this point that the detective begins investigating the premises himself.
Source Page – Wikipedia