Beloved priest Father Thomasino is murdered in a San Francisco alley, and the police have few clues. But traffic cop Joe Martini becomes obsessed with finding the killer; he suspects Sylvio Malatesta. Ordered off the case, Joe turns in his badge and investigates alone. Soon he is a close friend of the Malatesta family, all delightful people, especially lovely cousin Anna. Uncertain whether Sylvio is guilty or innocent, Joe is now torn between old and new loyalties.

A scrappy fighter from Jersey City named Tommy Shea -- "born in a dump, educated in an alley" -- catches the eye of wealthy businessman, Robert Mallinson, who allows him to train at his Long Island estate. Shea soon falls for Mallinson's daughter, Dorothy, but fears he doesn't have the money to support her in proper style. To get this money, Shea decides to work with crooked fight-promoter Harry Cram, even though this means dropping his honest manager, Dave Bernstein. As the big fight approaches, however, Shea begins to have second thoughts.