Police officers face many challenges in the decaying, impoverished, high-crime South Bronx region of New York City. Among these officers are NYPD officers Murphy (Paul Newman) and Corelli (Ken Wahl), who work out of the 41st Precinct, nicknamed “Fort Apache” because to those who work there, it feels like an army outpost in foreign territory. The streets are filled with dangerous gangs, criminals, and drug dealers. Unemployment is very high and the neighborhood is filled with garbage and wrecked buildings. While Murphy is a hard-drinking and lonely divorced father, he has a great camaraderie with Corelli. Murphy’s life also improves when he meets a young nurse, Isabella (Rachel Ticotin), and they start a romantic relationship.
The precinct is one of the worst and most dilapidated in the entire department, approaching demolition and staffed mostly by officers who are unwanted by, and have been transferred out of, other precincts. Additionally, the precinct’s officers do not represent the large Puerto Rican community, as only 4% of the officers are Hispanic in the largest non-English speaking section of The Bronx. Corelli and Murphy attempt to maintain law and order by catching pimps and robbers, but they have conflicts with corrupt fellow officers, and a newly appointed police captain, Connolly (Ed Asner). There is rioting due to alleged police brutality, as well as issues related to the deaths of two rookie cops, who were shot by a drug addict at the film’s beginning. During the riot, Murphy and Corelli witness an officer throwing an innocent teenager off an apartment roof to his death. As Murphy becomes more intimate with Isabella, they begin a sexual relationship. While she is sleeping, Murphy notices “track marks” on her skin. She later admits that she uses heroin as a way to relax from working in such a stressful environment. She tells him that other hospital employees also use heroin.
Illustrating the futility of policing in the precinct, the killer of the two cops is never found, despite mass arrests and interrogations. The drug addict who killed them is later also killed and her body is shown as an anonymous bundle dumped in roadside trash. Murphy is broken when Isabella dies from a drug overdose and wrestles with the moral question of whether he should maintain the “blue code” and not inform authorities about the officer who threw the teen off the roof. Murphy decides to resign and report the killing, a decision that will make other officers hate him and view him as a “stool pigeon”. Murphy seems to be on the verge of quitting the force, when he sees the purse snatcher fleeing from a house he burglarized. Murphy and Corelli chase the robber, and the image freezes as Murphy leaps to tackle him.