The Sins of St. Anthony (1920)

Young scientist Anthony Osgood is engaged to Persis Meade, who has postponed their marriage several times after becoming interested in an overseas hero through Red Cross correspondence. Meanwhile, gambler Lorenzo Pascal stumbles upon the hero's suitcase and goes to Persis' home impersonating him. When Anthony calls and finds his fiancée in another man's arms, Persis explains that he lacks pep. This sends him to dancer Jeanette Adair for help in making him over. Under Jeanette's tutelage, Anthony embarks upon a career of jazz parties and succeeds in changing his image. Discovering that her hero is a fraud, Persis tries to go back to Anthony but she is too late, for he has fallen in love with Jeanette.