A young woman develops a dangerous, obsessive friendship with her new roommate and plots to murder all those who she feels have done her new friend wrong.

In New York, the PRs colleagues and roommates Holly Parker and Jan Lambert are disputing a promotion in their agency. The unethical Jan deceives Holly and sends her to Chicago; meanwhile, she seduces Holly's boyfriend David Kray, in the opening of the fancy restaurant of his own, and they have one night stand. When Holly arrives back home, she finds that David cheated her with Jan, and she decides to move to a new apartment. She schedules a visit with the needy Tess Kositch, and they become roommates and friends. When Tess cuts and dyes her hair identical to Holly's style, she sees that her new roommate is obsessed on her. When Holly follows Tess to the underground night-club "Sin", she realizes that the girl is deranged. But Tess wants to be her friend and put Holly out misery, eliminating her former bad friends.—Claudio Carvalho, Rio de Janeiro, Brazil