As popular champion boxer Midge Kelly enters the ring to defend his title, his career is recalled: While riding a railroad boxcar toward California, where they have bought a third interest in a diner, Midge and his partially disabled brother Connie are robbed and ejected from the train. The next morning, Midge and Connie meet boxer Johnny Dunne and his girl friend, Grace Diamond, who give them a ride to Kansas City. When they arrive there, Dunne suggests that they could get jobs as concession salesmen at his fight that night. However, the refreshment manager does not want them and, when he calls Connie "gimp," Midge attacks him. Meanwhile, promoter Hammond learns that one of his boxers cannot fight due to an injury and realizes that Midge could be a substitute fighter in a bout in which he will be "carried" by his opponent. Hammond promises Midge thirty-five dollars and he survives a beating for the four-round bout. After the fight, Los Angeles manager Tommy Haley approaches Midge and offers to manage him, stating that while Midge has no great boxing ability, he does have "guts." Midge declines the offer and he and Connie eventually reach the diner in Malibu. They soon discover that their "partner" did not own the diner but was merely an employee, and has since been fired by owner Lew Bryce. Lew nonetheless hires Midge and Connie and gives them room and board, but warns them to stay away from his daughter Emma, who works as his waitress. Later, however, Midge invites Emma for a swim after work and a romance develops. When Emma brings up the subject of marriage, she discovers that Midge is not considering it, as he cannot support her. However, Lew discovers them together and, at gunpoint, forces them to marry. Immediately thereafter, Midge leaves with Connie. Needing work, they find the now retired Haley at a gym, and although he warns them about the dangers of the boxing business, Midge persuades Haley to become his manager. In his first fight, the well-trained Midge easily knocks out his opponent. Connie does not like Midge's new brutal and ambitious behavior and suggests that he quit, but Midge will not consider that. After several more successful fights, Midge buys an apartment for his mother and, over the next two years, works his way up the rankings until he earns a chance to fight the number one contender, Johnny Dunne. Haley then tells him that he must lose to Dunne, who will then go on to take the title, but that in a year or so, he will get a legitimate shot at the championship. Midge agrees to go along, but knocks Dunne out in the first round. After the fight, Midge, Connie and Haley are attacked by several thugs working for the gamblers who control the boxing racket. Later, Midge receives a phone call from the gold-digging Grace, who has decided to switch her affections to him. Unknown to Midge, she is working for Dunne's manager, impresario Jerome Harris, and assures him that she can persuade Midge to change managers. Grace then plays "hard-to-get" with Midge, but offers to stay with him if he drops Haley as his manager. When he does so, both Haley and Connie are disappointed and Connie walks out. Later, Connie goes looking for Emma and finds her working as a cocktail waitress. She has not divorced Midge and tells Connie that she is still interested in him and agrees to accompany Connie to Chicago to see his ailing mother. After Midge becomes the new champion, he begins an affair with Harris' wife Palmer, an amateur sculptor. Jealous, Grace insists that Midge marry her, but he tells her that he already has a wife. In Chicago, meanwhile, Emma realizes that she no longer loves Midge and now is in love with Connie. Midge learns from Harris, to whom he owes a lot of money, that he is to defend his title against Dunne, who has made a great comeback. Harris offers to forgive Midge's debt, tear up their contract and give him the entire purse from the fight, but only if he agrees to stop his affair with Palmer. When Midge accepts, Palmer is disillusioned. After Midge learns that his mother is dying, he asks Haley to train him for the fight, and Haley agrees to return in exchange for a third share. Midge then heads for Chicago, but arrives too late to see his mother. When Connie tells him that he and Emma intend to get married, Midge appears to be pleased and asks Connie to come back and help him prepare for the fight. At the training camp, however, Midge forces himself on Emma. Just before the fight, Connie tells Midge that Emma has left and that he stinks from corruption, then hits him. Midge slugs him back, but Connie recovers and goes to watch the fight. Dunne suffers an early knockdown, but revives and takes control of the fight. Although Midge is knocked down twice and suffers a badly cut eye, he refuses to throw in the towel and manages to knock out Dunne and retain the championship. In the dressing room, Midge is obviously punchy and imagines that he is back at the start of his boxing career, then collapses. Emma arrives at the arena in time to hear Haley announce to the press that Midge has died of a brain hemorrhage. Before walking off with Emma, Connie dourly informs the reporters, "He was a champion. He went out like a champion. He was a credit to the fight game to the very end."