Johnny and girlfriend Frankie are singers on a Mississippi riverboat, which also has a casino. Johnny is a gambler who is down on his luck and in debt.
Johnny and his friend Cully, a musician and composer, visit a gypsy camp to get his fortune told. A lady reads tea leaves and tells Johnny that he will soon meet a red-haired woman who will bring him luck.
Back on the boat, Johnny and Cully meet Nellie Bly, their boss Clint Braden’s on-again, off-again girlfriend. Nellie catches Braden seducing another singer, Mitzi. Since she has red hair, Johnny persuades Nellie to touch his chips for luck. After he wins, Johnny is convinced that the gypsy must be correct.
Frankie finds out and becomes jealous, as is Johnny’s boss. In a bit of musical theatre, Frankie shoots Johnny for dancing with Nellie Bly, while singing Cully’s new song. A Broadway recruiter sees the riverboat show and buys the rights to this new song, suggesting that Frankie and Johnny should work together in New York.
Landing in New Orleans, the musical cast and riverboat crew attend a masked ball. Frankie, Nellie and Mitzi all rent the same Madame Pompadour costume.
Johnny wants the luck of redhead Nellie to win more money, contrary to Frankie’s expressed wishes. Being masked and in costume, Frankie and Nellie switch places. Johnny wins ten thousand dollars at a roulette wheel, but when he kisses the woman he believes to be Nellie, he discovers the switch. Frankie is furious. She throws the ten thousand dollars out the window.
Blackie, who works for the boss, hears Braden drunkenly complain about how he has lost Nellie, so Blackie switches the blank in Frankie’s stage gun for a real bullet. The boss tries to prevent the impending disaster, but arrives at the theatre too late. Frankie has shot Johnny for real. Frankie forgives his gambling as he lies on stage. Johnny then stands up, apparently unhurt. Johnny was saved because he was wearing a lucky medallion that Frankie had given him, which the bullet struck.