Having recently split from fiancé Sam Rawson (Steven Weber), Allison Jones (Bridget Fonda) welcomes new roommate Hedra Carlson (Jennifer Jason Leigh). The young women quickly form a bond, but as Allison starts to rethink her engagement, Hedra grows jealous and hostile. As Allison learns new details about her roommate's life, Hedra gets violent in her efforts to get Sam out of the picture. With Hedra turning more menacing by the minute, Allison finally understands what she's up against.