On a beach outing, Rosie O'Reilly, her friend Ruth, and her sweetheart, boxer Joe Hennessey, meet Kid Farrell, Joe's trainer, and a fortune-teller predicts Rosie's fame as a dancer. Rosie creates an act and gets it booked for a cabaret. In a misunderstanding over a diamond pin given her by Lew McKay, a cafe habitué, Rosie is jailed for stealing, but Arthur Russell identifies the jewel and rescues her. Impressed by Arthur's wealth and social position, Rosie soon forgets Joe, who then begins to study etiquette, but to no avail. On the night of Joe's big fight, Rosie, losing interest in Arthur's party, goes to the ring, diverts the attention of Joe's opponent, and thus assures Joe's final victory.