A New York City architect becomes a one-man vigilante squad after his wife is murdered by street punks in which he randomly goes out and kills would-be muggers on the mean streets after dark.
Paul Kersey has managed to recover from his shattered life and moved on, and is now dating L.A. radio reporter Geri Nichols. They go to pick up Kersey's daughter Carol from the mental hospital. They spend the afternoon at a fairground, where Paul's wallet is stolen by a gang consisting of Nirvana, Punkcut, Stomper, Cutter, and Jiver. The gang split up when Paul chases them; he goes to pursue Jiver, whom he corners in an alley, but lets him go after Jiver tells him that he does not have the wallet.
Paul Kersey (Charles Bronson) returns to New York City after being banned Death Wish (1974 film) to visit his Korean War buddy Charley, who is attacked by a gang in his East New York apartment. The neighbors hear the commotion and call the police. Paul arrives and Charley collapses dead in his arms. The police mistake Paul for the murderer and arrest him. At the police station, Inspector Richard Shriker (Ed Lauter) recognizes Paul as "Mr. Vigilante". Shriker lays down the law before Paul is taken to a holding cell. In the same cell is Manny Fraker (Gavan O'Herlihy), leader of the gang who killed Charley. After a fight between him and Paul, Manny is released. The police receive daily reports about the increased rate of crime. Shriker offers a deal to Paul: he can kill all the punks he wants, as long as he informs Shriker of any gang activity he hears about so the police can get a bust and make news.
Erica Sheldon (Dana Barron), the teenage daughter of Karen Sheldon (Kay Lenz), Paul Kersey's current girlfriend, goes with boyfriend Randy Viscovich (Jesse Dabson) to an Amusement arcade to meet up with a man named JoJo Ross (Héctor Mercado) and another buddy, Jesse Winters (Tim Russ). JoJo offers her crack cocaine, and Erica dies from an overdose. Having seen Erica smoke a joint with Randy while in his car the previous night, Paul suspects Randy was involved with Erica's death, so he follows him to the arcade. Randy confronts JoJo and threatens to go to the police. JoJo murders Randy to prevent this. Paul promptly shoots JoJo, who falls onto the roof of the Bumper cars and is fatally electrocuted.
Paul Kersey (Charles Bronson) returns to New York City, having assumed the name Paul Stewart under the witness protection program. He is invited by girlfriend Olivia Regent (Lesley-Anne Down) to a fashion show. Backstage, mobster Tommy O'Shea (Michael Parks) and his goons muscle in. Tommy threatens Olivia, who is his ex-wife and mother to their daughter Chelsea (Erica Lancaster). Olivia later informs Paul of her ex-husband's behavior after he finds bruises on her hand. Paul confronts him, but Tommy's henchman Chicki Paconi (Kevin Lund) pulls out a Colt King Cobra at Paul. The confrontation ends with the arrival of Chelsea.