Lucy Smith (Christina Ricci) reluctantly makes her way to her father's home in Beverly Hills after his fatal heart attack. Unfortunatley, a group of rowdy teenagers arrive next door for a party weekend. Shortly thereafter, the killings begin.
Lucy witnesses her 'strange' brother David in the neighborhood and figures out that he must be the killer. She confronts him in the house, where they get into a struggle. Suddenly, Rachel rushes out and stabs David with a meat hook. As he falls to the ground, Lucy thanks Rachel for saving her. However, Rachel then attempts to kiss Lucy and reveals that she was the true killer. Lucy resists her and Rachel declares that Lucy must now die. In the ensuing struggle, Lucy in stabbed in the leg. Before Rachel can finish her, though, David rams into her and they fall into the pool. Just as Rachel stabs David over and over, Lucy smashes her over the head with a potted plant. Rachel is arrested by the police as she shouts out at Lucy that she loves her and is sorry for trying to harm her, but Lucy turns her back, causing Rachel to shout that she will kill her. She is then taken away by the police.