In New York City, a waitress is attacked by muggers on her way home. When she seeks help from an officer on the beat, he breaks her neck. When the same officer (Robert Z’dar) commits further murders, Lieutenant McCrae (Tom Atkins) is assigned to investigate. He is told by his superiors to suppress eyewitness accounts that the killer is wearing a police uniform. However, he passes this information to a journalist, in an attempt to protect civilians. Ellen Forrest (Victoria Catlin), suspects that her husband Jack (Bruce Campbell) may be the “Maniac Cop”, as the press are calling him, and follows him to a motel, only to discover he is having an affair with fellow officer Theresa Mallory (Laurene Landon). Ellen is subsequently murder by the killer and Jack is arrested under suspicion of murder. McCrae believes Jack has been framed and speaks to Mallory, who can provide Jack with an alibi. Mallory is then attacked by the Maniac Cop while working undercover as a prostitute. McCrae and Mallory fight off the killer, who escapes mysteriously unharmed, despite being shot several times.