Billy moves into Freddy's old house with his mother and stepfather. While his parents are gone for the weekend, Billy has to watch the house. He sees a pretty teenage girl, Barbara from across the road and eventually talks him into throwing a party in his house. As the party progresses the problems get more out of control as Billy's stepfather's most prized possessions are systematically destroyed one by one. The party turns out to be a bad dream, but the real nightmare is about to begin, as Billy accidentally falls out of an upstairs window.