Chronic gambler Joe Beebe (Bing Crosby) is a source of great consternation for his loving mother (Elizabeth Patterson), who wishes that Joe would follow the example of his responsible, strait-laced brother David (Fred MacMurray). Meanwhile, the youngest member of the Beebe clan, 13-year-old Mike Beebe (Donald O'Connor, in his first major film role) unabashedly hero-worships the wastrelly Joe. It so happens that all three brothers are talented musicians, but only Joe has star quality. Heading to Los Angeles to seek his fortune, Joe promises that he'll send for the rest of his family when he makes good. Inspired by the glowing reports of his success in L.A., Mother Beebe sells everything she owns and heads to the coast--only to discover that the prodigal Joe has spent every penny he's earned on a long-shot race horse. While Joe tries to groom the nag for the big money--with Mike as the jockey--middle brother David arrives in L.A., prepared to knock some sense into Joe's head. As things turn out, the brothers join forces to thwart a bunch of race-fixing gangsters, segueing into the long-delayed happy ending. Heavily touted as the first film in which Bing Crosby played a "serious" role (which it really wasn't) Sing You Sinners is best known today for introducing the hit songs "Small Fry" and "I've Got a Pocketful of Dreams.""