An African-American drug addict named Fletch takes his friend, Leroy Fisk, to a barber shop and introduces him as a “tough guy” to Mr. Logan, a white gangster. When Logan’s thugs, Avon and Earl, call Leroy a punk, he threatens to beat them up. Logan asks Leroy if he wants to “streetfight,” which is not the same as boxing, because streetfighting is with bare-knuckles and has no rules. Leroy says he can beat anybody, but he will not do it for “chump change.” On a rooftop, Leroy fights a large white man named Moose, who beats him. Logan then invites Leroy to his apartment, tells him he has promise but needs work, and hires him for his streetfighting “stable.” Leroy calls his wife, Bea, to tell about the job, but she refuses to talk until he comes home. Angry, Leroy visits the apartment of his girlfriend Florence, whom he calls “Flo,” and impresses her with his cash. Meanwhile, a plainclothes police detective named Heineken meets Fleichman, a streetfight manager, to receive a payoff, but Fleichman is short a few dollars and promises to make it up next time. Logan turns Leroy over to Ira, one of his veteran streetfighters, for training. At Ira’s gym, Leroy learns the aggressive tactics of the job. For Leroy’s “coming out,” Logan and Fleichman set up a winner-take-all streetfight at a trucking warehouse between Leroy and Pak San, one of Fleichman's fighters, and Leroy wins. Fleichman calls local gangster Ingo, promising to pay the money he owes when he gets it. Ingo then dials another number to order Fleichman killed. A man follows Fleichman into an elevator and murders him. Avon delivers a suitcase of money to Logan, who turns it over to Leroy. Later, Detective Heineken visits Leroy at a pool hall, remarks that he has seen him fight, and reminds him that street fighting is illegal. If Leroy wants to keep fighting, he will have to make Heineken his partner and share a cut of his winnings. Sometime later, a crowd pays to get into a lumber yard, where Leroy surprises his opponent by beating him. Afterward, Leroy takes Flo shopping and makes love with her at her apartment. Back at the pool hall, Heineken drops by for his payoff and reminds Leroy that he could not stay in business without Heineken as his partner. When Leroy complains to Logan about the payoffs, Logan assures him that he will deal with Heineken, but for the time being he will give Leroy extra fights to make up for the losses. Ira later pulls Leroy aside and tells him that Heineken and Logan are partners and that Heineken pays half of Leroy’s payoff money back to Logan. When Leroy goes to a nearby park to get drunk, his friend, Fletch, comes by to say he has done Leroy a big favor. Fletch gives him Heineken’s private book of handwritten payoffs from streetfighters, prostitutes, and gamblers, which Fletch stole from the detective. Meanwhile, Heineken complains to Logan that somebody stole his private ledger, which has enough information to get them both into trouble. Leroy later calls Heineken and tells him to come to his apartment. When Heineken arrives, Leroy shows him Fletch's body, the result of an overdose. He gives Heineken a page from the ledger to show he has it, and tells the detective he is not paying him any more money. Heineken calls a friend at the morgue, then demands that Leroy return his ledger, but Leroy orders the detective out of his apartment. When Leroy also ends his partnership with Logan, the gangster telephones him at Bea’s apartment and offers one last fight with Moose, the man who beat him during his first fight. Despite Bea's protests, Leroy agrees under the condition that Logan pays an extra $25,000 if he wins. Logan calls Ingo and tells him to bet $50,000 on Moose. Later, Leroy visits a gambler named Big Henry and learns that people are betting against him, even Logan, and if he loses the fight, he had better die in the process. However, Leroy makes his own bet with Henry, putting all his money on himself. When the fight is held at a junkyard before a crowd of several hundred spectators, Leroy defeats Moose. Despite Avon’s attempts to stop him, Leroy retrieves a suitcase full of money from Logan, who then telephones Ingo to say he cannot compensate for Ingo's losses, but promises to pay soon. Meanwhile, Leroy buys a nightclub, invites Bea and her brother, Everett, to attend an opening night celebration. Afterward, Leroy sends Bea and Everett out to his car ahead of him, and the vehicle explodes, killing them. Logan celebrates with Avon, Earl, and a female drug addict named Ginger until they hear that Leroy survived the bomb and went underground. Logan sends Avon and Earl to hunt Leroy, who watches Bea’s funeral from a hiding place and leaves town. When Leroy returns, he stays at Flo’s apartment, disguises himself with a fake beard and sunglasses, and goes after Logan’s men. Hearing that an addict named Boom Boom put the bomb in his car, Leroy finds him in a bathroom and beats him, but Boom Boom claims innocence. Leroy breaks into Earl’s apartment and beats him, too, then drives Earl to an empty drive-in movie theater, pours gasoline on him, and blows up the car. When Leroy returns to Boom Boom, he learns that Logan is in debt to Ingo. Leroy gives Boom Boom Flo’s phone number and tells him to call if he hears anything. Later, Heineken and Logan take Boom Boom to a junkyard and he gives them Leroy’s phone number, but they kill him anyway. With police access to telephone records, Heineken traces the number to Flo, and while he tries to rape her and find out where Leroy is, Leroy arrives and beats him unconscious. He takes the detective to a meat packaging warehouse, hangs him on a hook in a meat freezer, and puts his ledger in his pocket to be discovered by police. Meanwhile, Avon drives to Ingo’s beach house to tell him he killed Logan and wants to work for him. Ingo makes a telephone call to lure Leroy to his beach house, claiming that Logan is there. When Leroy drives to Ingo’s, the gangster tells him to look through a small telescope that reveals Avon’s body submerged in a swimming pool. Ingo tells Leroy that he arranged Logan’s death, and claims that Leroy is now working for him, but Leroy says he knows that Ingo arranged the deaths of Fletch and Bea, pulls out his gun and kills the gangster. Realizing his dreams of wealth have destroyed Bea's life and nearly his own, Leroy smashes his own image in Ingo’s wall of mirrors with his fists.