The film begins with a stunning panorama of Los Angeles, accompanied by a news report highlighting a troubling surge in crime within the city. As the credits roll, our focus shifts to Paul Kersey, portrayed by Charles Bronson, at his new home. The house is bustling with activity thanks to the maid, Rosario (Silvana Gallardo), as she prepares dinner. Paul seems to have finally begun to piece his life back together, romantically involved with Geri Nichols (Jill Ireland), a KABC news/radio reporter. The couple also takes a trip to the hospital to greet Carol (Robin Sherwood), who has recently been undergoing treatment.
During a conversation with the doctor, Paul learns that despite her earlier traumatic catatonia, Carol is beginning to regain her ability to speak. It's mentioned that her husband, Jack Toby, is presumably out of the picture. The three later enjoy a lively day at a carnival, where Paul leaves briefly to purchase ice cream. However, while in line, he falls victim to a robbery orchestrated by five gang members who not only snatch his dollar bill but also steal his wallet. Initially unfazed, he later realizes the severity of the situation as he attempts to chase one of the thieves, Jiver (played by Stuart K. Robinson).
While Geri heads off for an interview with a senator, Paul and Carol embark on a boat ride. Unbeknownst to them, the very gang members who robbed Paul are determined to eliminate him. They break into his home, binding and gagging Rosario before brutally assaulting her. When Paul arrives home with Carol, he is ambushed and knocked unconscious. Rosario, in her attempt to call the police, becomes a victim when the criminals bash her head in. They subsequently abduct Carol, leading her to a horrific encounter before she escapes by jumping from a window, only to suffer grave injuries.
As Paul regains consciousness, he finds Geri at his side, with the police arriving shortly after. Lt. Mankewicz (Ben Frank) questions Paul about the culprits, but his description is somewhat vague. In the wake of Carol's death, Paul is taken to the station for identification purposes but dismisses Mankewicz's request to view mug shots, stating, > "it won't do any good."
The tone shifts at a funeral attended by both Paul and Geri. That night, driven by rage and sorrow, Paul retrieves a concealed .32 caliber semi-automatic handgun from his closet. He rents a cheap apartment in the inner city to serve as his operational base for vengeance. The following day, after almost getting discovered by Geri, he takes precautionary steps, including changing the locks on his home.
His journey into vengeance truly begins when he spots one of the gang members, Stomper (played by Kevyn Major Howard), and stalks him to an abandoned hotel where a drug deal is taking place. Attempting to remain unnoticed, Paul accidentally alerts the group to his presence, leading to a fight where he kills Stomper and his partner in self-defense.
On another night of patrol, Paul hears a woman’s scream in an underground parking garage. Upon rushing in, he sees several muggers attacking a man and a woman. Among them is Jiver, and in a furious confrontation, Paul takes out two of the muggers, severely wounding Jiver, who narrowly escapes. Determined, Paul tracks down and finishes him off at a nearby warehouse.
As the police catch wind of the vigilante killings, Detective Frank Ochoa (Vincent Gardenia) from the NYPD is brought in to assist the LAPD, suspecting Paul to be behind the murders. Ochoa investigates further, uncovering Paul’s past that makes him suspect a deeper connection to the events.
Complications arise as Geri becomes entangled in Ochoa's investigation, while Paul, unaware of the scrutiny, still pursues justice against the remaining gang members: Cutter ([Laurence Fishburne]), Punkcut ([E. Lamont Johnson]), and Nirvana ([Thomas F. Duffy]). During a tense drug deal at an abandoned park, Paul faces off with these criminals, leading to a chaotic shootout in which more than one life is lost—including that of Ochoa, who tries to save Paul but ultimately meets a tragic end.
In the aftermath, with the police growing increasingly suspicious, Paul learns of Nirvana’s potential location thanks to police radio chatter. As he makes desperate attempts to find him, he inadvertently gets injured but is determined to catch him first. When Nirvana is finally arrested following a violent altercation, the law sends him to a psychiatric facility, which becomes vital for Paul’s plan for revenge.
The tension climaxes when Paul infiltrates the hospital to confront Nirvana, where they engage in a brutal struggle. Paul ultimately manages to strike back by electrocuting Nirvana, securing his own revenge while ensuring his escape. But as Paul returns to a sense of normalcy, it's revealed that Geri has discovered his secret life—driving a wedge between them as she leaves him.
The movie concludes with an enigmatic scene showcasing Paul at work, seemingly back to his routine. When asked about the evening's plans, he quips, > "What else would I be doing?" As the sound of gunfire echoes in the background of L.A.'s skid row, the implication is clear: Paul Kersey will persist in his quest for vigilante justice, undeterred and relentless.
