Description
Alex is a serial-killer driving around New York City at night when he spots a young woman, Susan, driving alongside him. He follows her to a nearby park where he rapes her before strangling her to death. He takes her locket as a trophy to another one of his many killings.
Some time later, Alex and his friend Ricky are closing up the underground garage where they both work, planning to go to a local disco. Before they can leave, a Cadillac pulls in with a young, well-dressed couple, Tom and his girlfriend Lisa, asking for help with their car. Alex refuses to help them, saying that the garage is closed, but the slow-witted Ricky decides to help and easily fixes the problem. Tom tells Alex and Ricky that they are driving to a friend's house in New Jersey for a party, and invites them along. Before leaving, Alex stops by his locker, which is filled with various weapons he uses to murder people, and takes a straight-edged razor.
The four arrive at a large villa where they are welcomed by the owner, Gloria, and her friends Glenda and Howard. Minutes later it becomes obvious to Alex and Ricky, that the rich people are looking for easy thrills. Gloria asks Ricky to do a striptease to some disco music and he makes a fool of himself, and is further humiliated by being goaded to drink alcohol with each move. However, Alex stops Ricky before he strips completely naked. Tom, Howard and Glenda next play poker with Ricky, while Lisa begins sexually teasing Alex and invites him upstairs to shower with her, only to push him away. As Alex grows more frustrated, he sees that the hosts are cheating at poker with Ricky. Alex pulls out the straight-edge razor, and a fight breaks out between him and Howard. Alex throws Howard outside the back door, beats him viciously, and throws him into the pool. Laughing, Alex urinates on Howard and drags him back inside, tying him to a piano leg and proclaiming that he is running the party now.
Alex and Ricky proceed to beat on their hosts-turned-hostages with Alex slashing Tom's face with the razor and beating his face into the poker table. Ricky holds the others at bay with a wine bottle while Alex sexually assaults both Gloria and Glenda. Lisa runs to an upstairs bedroom where she tries to escape, but Alex catches her and proceeds to rape her. When Alex takes Lisa downstairs to rejoin the others, the doorbell rings. Alex forces Gloria to answer; when she opens the door, it's their teenage neighbor, Cindy. Alex grabs Cindy, while Gloria tries to escape. Ricky, still holding the broken wine bottle, runs outside after Gloria and catches her, showing Gloria that he means her no harm by tossing aside the wine bottle. Gloria responds to his simple nature by taking off her clothes and seducing him.
Inside, Alex cuts Cindy's blouse off with the razor while singing. Ricky then returns to the house with Gloria just as Alex forces Cindy to strip off the rest of her clothes, and proceeds to savagely slash her with his razor over and over again. At this point, Ricky comes to a realization and attempts to stop Alex. Upset at being betrayed by his friend, Alex turns against Ricky and slashes his abdomen wide open, and then breaks down in regret.
Bloodied and battered, Tom runs into the nearby study and pulls out a 9mm pistol out from a desk drawer. Tom shoots Alex a few times, then kicks him through the glass back door. Gloria and the other women untie Howard, and the five descend upon the fatally wounded Alex lying on the ground. Tom removes the locket Alex is wearing and reveals the reason for all this: the woman that Alex raped and murdered at the park is Tom's sister and Tom wanted revenge. He and Lisa wanted to lure them to Gloria's house so they could kill them and make it look like self-defense. After shouting at him, Tom shoots the wounded Alex in the groin, making him fall into the swimming pool. Tom and Lisa take turns shooting Alex, who thrashes weakly in the water, before a final bullet to the head by Howard finishes him for good.
Returning to the house, Gloria stops Howard from shooting Ricky, while Glenda tends to the wounded Cindy. Tom and Lisa go into the study where they talk about their plan. Tom says that despite some mistakes, that it worked out for the best, and then picks up the phone to call the police.
