Two police officers sit in their cruiser in the Bronx section of New York City when Charlotte, a prostitute, approaches and guns them down. At the police station, twenty-year veteran patrol officer Murphy, and his young partner, Corelli, learns that their precinct is getting a new captain named Connolly. Later, Murphy talks down a transvestite “jumper” from a high-rise roof and escorts him to the hospital. There, Murphy asks a nurse named Isabella to have a drink with him, but she turns him down. Later, Murphy chases a purse-snatcher, who outruns him and escapes. Two other officers, Morgan and Finley, appear and tell Murphy he should have shot the criminal. When Murphy protests that the media would crucify him for shooting an unarmed man in the back, Morgan advises him that he should have planted a knife on the perpetrator and claimed self-defense. Connolly arrives at the precinct known as “Fort Apache,” the only outpost of “civilization” in the South Bronx. The cops are mostly disciplinary transfers from other precincts and often corrupt. Meanwhile, Murphy and Corelli see a pimp slapping Charlotte. When they stop the man, he offers the cops a bribe. Murphy smashes the headlights out of the pimp’s car with his baton. Later, they respond to a call and find a young Puerto Rican girl is giving birth. Murphy delivers the baby and takes the mother and child to the hospital. The nurse, Isabella, suggests that Murphy needs a drink, and asks him out. On their date, Murphy explains he was a detective, but got demoted after arresting a criminal who was paying off a police commissioner. They go his place and make love. Isabella falls asleep and Murphy sees needle marks on her legs indicating she is a drug user. On the streets, Charlotte finds an older man changing a tire and invites him into an abandoned building with the promise of sex. Instead, she slices his throat. Murphy and Isabella’s relationship grows more intense. He introduces her to his daughters and double dates with Corelli. One day at roll call, Captain Connolly orders his men to arrest everyone they see committing a petty crime, hoping they will get a lead on who killed the two cops. Murphy protests they will only anger the neighborhood, but he is overruled. Working plain clothes, Murphy and Corelli arrest a dealer in stolen goods, known as a “fence,” who tells them his neighbor is selling drugs. Upon arresting the dealer, they learn of a cock-fighting ring in the basement. This leads them to an alley full of prostitutes and their customers. Soon, their van is overflowing and Murphy commandeers a city bus to take everyone to the precinct jail. The mass arrests cause neighborhood protests. Connolly fires tear gas into the crowd, triggering a riot. Murphy spots two hoodlums hurling rocks and trash at firefighters from a rooftop. He and Corelli rush to the roof and arrest the men. They spot a young couple embracing on another rooftop as officers Morgan and Finley arrive. Murphy stares in horror as Morgan grabs the young man, beats him, and hurls him from the roof. When Murphy asks if Corelli witnessed the murder, he claims, “I didn’t see nothing.” That night, Murphy comes out of bar to find the purse-snatcher he pursued days earlier breaking into his car. Instead of arresting the boy, Murphy waves him off and drives away. The next day, Connolly calls in all the police that were at the fire and confronts them about the boy’s death, stating that witnesses saw a police officer throw the young man off the roof. Only Murphy fails to proclaim his innocence. That night, two drug dealers, Hernando and Jose, arrive at a brothel to collect money from the madam. Jose takes a liking to the drugged Charlotte and tries to have sex with her. She slices his cheek with a razor, and Jose stabs her in the stomach with his switchblade knife. Hernando and Jose wrap Charlotte’s dead body in a rug and take it away. Meanwhile, Murphy tells Morgan that he saw what happened, and the two fight, ending when their fellow officers intervene. The next day, Corelli warns Murphy that he will not testify against a fellow cop. Murphy spends the rest of the day with Isabella, and after making love, confronts her about her drug use. Instead of lecturing her, Murphy offers to get drugs for Isabella until she is ready to quit. As Murphy drives her home, he tells her about Morgan. She becomes angry and demands to be let out of the car. As she approaches her building, her dealers, Jose and Hernando, suspect she is collaborating with police and decide to kill her with a lethal level of heroin. The next day, Isabella takes the drugs and realizes something is wrong. She staggers out of her apartment and collapses on the sidewalk. Jose and Hernando go to hospital to make a sale, only to find their client is an undercover cop. They grab hostages and demand the cop put his gun down. Murphy and Corelli respond to the police call to find the pushers have barricaded themselves in an office with the hostages. When police attempt to negotiate, Jose shoots a doctor in the leg and demands to be set free. Murphy and another officer break through the door. Shots are fired and both drug dealers are killed. Realizing Isabella is not there, Murphy runs to the reception desk in time to see her lifeless body being carried in on a gurney. Refusing to believe Isabella is dead, Murphy attempts to wake her. Corelli takes her from Murphy’s arms and places her back on the gurney. Murphy returns to the precinct, hands in his badge and tells Captain Connelly that Morgan killed the boy. Connelly tries to talk Murphy into staying on the force, but he refuses. As he drives home, Corelli jumps up from the back seat, states he will back up Murphy’s story and asks him not to quit. Murphy claims he can no longer be a cop. But he sees the purse-snatcher climbing out a window. He and Corelli give chase, unknowingly sprinting past the rug in which Charlotte’s body is hidden.