Jobless sportswriter Eddie Willis is hired by corrupt fight promoter Nick Benko to promote his current protégé, an unknown Argentinian boxer named Toro Moreno. Although Moreno is a hulking giant, his chances for success are hampered by a powder-puff punch and a glass jaw. Exploiting Willis' reputation for integrity and standing in the boxing community, Benko arranges a series of fixed fights that propel the unsophisticated Moreno to #1 contender for the championship. The reigning champ, the sadistic Buddy Brannen, harbors resentment at the publicity Toro has been receiving and vows to viciously punish him in the ring. Eddie must now decide whether or not to tell the naive Toro the truth.

Gambler Nathan Detroit has few options for the location of his big craps game. Needing $1,000 to pay a garage owner to host the game, Nathan bets Sky Masterson that Sky cannot get virtuous Sarah Brown out on a date. Despite some resistance, Sky negotiates a date with her in exchange for bringing people into her mission. Meanwhile, Nathan's longtime fiancée, Adelaide, wants him to go legit and marry her.