On Christmas Eve in Los Angeles, a dispatched LASD Sheriff is shot dead by an armed robber, who early on robbed a convenience store and also killed its African-American owner. The alcoholic, hard-driven LASD Detective Jerry Beck is tasked with the investigation. While examining police records he comes across a person of interest named Bobby Burns, who has recently been paroled from a four-year robbery sentence. He and a parole officer go to Burns' home only to find his college student brother, John, who claims he has not seen Burns and is only staying for the holidays. A man suddenly flees the house and Beck captures him after a chase on foot; he turns out to be one of Burns' friend who is also on parole from committing armed robbery. The man tells Beck that he last saw Burns driving a maroon Ford Ranch Wagon en route to Bakersfield. In Arizona, Burns and his men rob a Mexican bar and kill its patrons. A local police chief informs Beck of the crime and he immediately leaves for Arizona. Beck and the chief head to a ranch alleged to be Burns' hideout, where Burns and his men attack the officers by firing automatic weapons; they escape driving the Ford. Beck retrieves a cache of documents Burns dropped, which contains white supremacy propaganda, maps, and an address book. Beck leaves for Oklahoma to track down one of the people listed in the book, Reverend Gebhardt, who is the leader of the religious white supremacist organization Aryan Nations. Beck is joined by FBI Agent Kressler and they head to Gebhardt's church, where Gebhardt reveals the entity's aim of cleansing America of its "racial impurities", and denies having seen Burns before. Burns, though, has been hiding near the church and casing the place. That night, Burns springs on Beck while driving his car and holds him at gunpoint. As Burns prepares to shoot him, Beck crashes his car into an oncoming police vehicle to escape. During a gunfight, Beck lights a matchbook and sets a car leaking gas on fire, causing Burns to escape with his men after an explosion. Back in Los Angeles, Beck's superiors have become frustrated over his performance on the force due in part to his alcoholism and uncouth behavior. They recommend he undergo a psychiatric analysis; after the session, though, Beck threatens the psychiatrist into letting him pass the evaluation. A phone call later that day informs him that he is now fit for duty. In Colorado he meets Police Captain Dixon, who entrusts his team of black men on the force to track Burns. Along with Kressler, he and Dixon head to a paramilitary training camp which is owned by the Aryan Nations, and ambush Gebhardt and the other members. His search for Burns yields no results, which causes hostility between him and Kressler. Beck, though, discovers a concealed door that leads to a bunker. A gunfight ensues between him and Burns; Beck shoots and fatally wounds him. As he lay dying, Burns reveals that he did not kill the Los Angeles cop. John emerges from behind and, as he prepares to shoot Beck and Kressler, confesses that it was he who shot the cop to show his brother that he shared his contempt against the police and fidelity to white supremacy. Beck hurls John insults about his brother, and John reciprocates by open firing at him. When John runs out of bullets and springs from cover, Beck shoots him dead. At a press conference, Dixon informs that the FBI will be revising its position on white supremacy groups, and he credits Kressler with the success of the investigation owing to the evidence the agent gathered. Outside, Dixon and Beck befriend one another and go their separate ways.
"Jerome Beck" is listed in the film's closing credits as walk-on character Detective John, and also as the film's technical police advisor. Don Johnson later recalled:
That was amazing, because it was a real-life character. It was an actual cop, and he wrote the script. John Frankenheimer was the director... and I was excited to work with him. Jerry was a homicide cop in L.A., and he had curly hair, so I permed my hair, which was a, uh, very interesting choice. Because I kind of looked like a… It’s kind of odd. I don’t really know how to describe it. I don’t know if you know a lot about perms, but if you do them, they relax after about two or three weeks. So my hair goes through these amazing transitions of being really tight and really wavy and sort of goofy-looking.
