Norah, a discotheque hostess living in New York City, receives a number of obscene phone calls. A vice squad detective, Bill Madden, takes a special interest in the case, and the hostess begins to suspect that he is the culprit. Norah befriends Lawrence, the busboy at the club, unaware that he is the sexually disturbed caller. He begins to watch her apartment through binoculars; the calls begin to come more frequently; and the terrified Norah is persuaded to move in with Bill and his daughter. One night, Billie, the club's owner, visits Norah, and Lawrence, mistaking her for the other woman, brutally rapes and murders her as she leaves the building. Bill, whose wife was murdered by a sex maniac some years earlier, tries desperately to track down the caller. One night while Norah is giving Lawrence dancing lessons at the club, he assaults her, thus identifying himself as the psychopath. He flees from the discotheque and is shot by police.