Early one morning in New York City, Nick Benko, the venal head of a boxing syndicate, offers washed-up sportswriter Eddie Willis the job of promoting Benko’s new find, a towering giant from Argentina named Toro Moreno. While watching Toro work out in the ring, Eddie comments that the giant possesses a powder puff punch and a glass jaw, to which Benko matter-of-factly replies that he plans to fix all of Toro’s fights to generate revenues. Broke and unemployed, Eddie accepts Benko’s offer and suggests kicking off the campaign in far off California. Although Eddie’s wife Beth objects that working as a press agent is beneath him, Eddie heads for California with the good-natured, trusting Toro and the boxer’s loyal manager, Luis Agrandi. In Los Angeles, Eddie fabricates a web of lies about the unknown boxer’s triumphs and parades him around in a bus bearing his image. Eddie asks his old friend, sportscaster Art Leavitt, to join him at Toro’s first match against Sailor Rigazzo, a contender for the heavyweight crown. When Rigazzo realizes that he can handily beat the lumbering Toro and refuses to throw the fight, Rigazzo’s manager blinds him with a towel doused in chemicals, assuring the boxer’s loss. When Toro is declared the winner, Rigazzo kicks the towel toward Art, who detects the odor of chemicals and calls for an inquiry. Upon learning that he is to be investigated, Benko offers Eddie ten percent of the profits to quash the hearing. Unable to resist the lure of financial security, Eddie goes to see Art and asks him to withhold his testimony. Art responds by showing Eddie an interview he has filmed with a destitute, punch-drunk boxer, who was cast aside by his boxing managers once he had outlived his usefulness. Then, as a favor to Eddie, Art agrees to say that the match could have been honest. Afterward, when Jim Weyerhause, the spokesmen for the managers, demands a bigger cut of the gate, Eddie, influenced by Art’s film, insists on paying the boxers directly. Weyerhause, who views boxers as little more than animals, at first objects, but finally accedes to Eddie’s terms. As Toro crosses the West, defeating all his opponents, excitement builds in the press. When Beth asks Benko for permission to join her husband, Benko demurs on the grounds that her presence would impede Eddie’s momentum. Benko and Beth finally join the tour in Chicago, where Toro is to meet Gus Dundee, the recently defeated champion. There, Agrandi, who has not seen a penny of Toro’s winnings, asks Benko for money to send home to Toro’s mother, but Benko denies his request. Upon meeting with Gus, Eddie is disturbed to find that the former champion has not yet recovered from his debilitating defeat by Buddy Brannen, and still suffers from splitting headaches. Annoyed by Agrandi’s advocacy of Toro, Benko has the manager’s visa revoked, thus forcing him to return home to Argentina immediately. That night, Eddie is awakened by a phone call informing him that Toro has run away. When Eddie finds Toro, surrounded by a band of Benko’s bat-wielding thugs, Toro begs to go home. After his promises of fame and fortune fail to placate Toro, Eddie vows that they will both quit after Toro fights Buddy for the championship. Although Gus has a severe nosebleed, he is forced to face Toro in the ring. Unable to defend himself, Gus staggers and then collapses to the boos of the bloodthirsty crowd. After he is carried off in a coma, Gus is diagnosed as suffering from a preexisting hemorrhage aggravated by Toro’s blows. Although he was fully aware of Gus’s condition, Benko blames the boxing commission and referee for the boxer’s injuries, and then uses Gus’s downfall to glorify Toro. After Gus dies on the operating table, Beth asks Eddie to quit and return to New York with her, and when Eddie insists on staying to the end to collect his payoff, Beth leaves him in disgust. At a press conference before the championship bout in New York City, Buddy, angry that Toro was credited with Gus’s demise, boasts that he killed Buddy and that Toro will be his next victim. Soon after, a priest summons Toro to his church and shows him a letter from Mrs. Moreno, asking her son to come home and atone for killing a man. When Toro pleads to return to Argentina, Eddie plays on his guilt by reminding the boxer of his obligations to the syndicate. Concerned about Buddy’s threats, Eddie finally tells Toro that all his matches have been fixed, and to prove his allegations, directs George, the over-the-hill boxer who has trained Toro, to deck the fighter with one punch. Eddie then instructs Toro to stay down for the count with Buddy and throw the fight. Disregarding Eddie’s advice, Toro slugs back, enraging Buddy who delights in brutalizing the hapless boxer. After Toro is carried from the ring with a broken jaw, George comments that some guys can sell out while others cannot. After the match, Eddie goes to collect his share of the proceeds and is handed $26,000 by Leo, Benko’s bookkeeper. When Benko announces that he has sold Toro’s contract to Weyerhause for $75,000, Eddie asks for Toro’s earnings and is given $49.07. Outraged, Eddie goes to the hospital to take Toro home. Still trusting Eddie, Toro confides that he plans to buy a house for his mother with his share of the earnings. Ashamed, Eddie hands Toro his $26,000 and then puts him on a plane for Argentina. Eddie then goes home to reconcile with Beth and soon after Benko pounds at the door and demands that Eddie reimburse him the $75,000 he had to repay Weyerhause. After Eddie retorts that he has decided to write an exposé of the boxing rackets, Benko threatens him and leaves. Slamming the door after Benko, Eddie sits down at his typewriter and begins to write.