In New York, Holly Parker and Jan Lambert, PR colleagues and roommates, compete for a promotion at their agency. Jan's deceit sends Holly to Chicago, while she seduces Holly's boyfriend David, leading to a one-night stand. Holly returns home to find David has cheated with Jan, and she decides to move. She meets Tess Kositch, a needy woman who becomes her roommate and friend. Tess's obsessive behavior and identical hairstyle raise suspicions, and Holly discovers Tess's dark obsession at an underground nightclub, "Sin".

Single White Female 2: The Psycho
A twisted bond forms between two women, culminating in one's sinister scheme to exact revenge on those she believes have wronged her roommate.