While his daughter Pauline attends school in France, Emil Cheraud establishes a fashionable gambling house in New York. Upon her return, Pauline begs her father to close the establishment, and he promises to do so that very night at midnight, but when she enters his library shortly after the appointed hour, she finds him dead. Determined to bring the murderer to justice, Pauline assumes control of the gambling house in the hope of trapping the criminal into a confession. Three men are suspected, all of them in love with Pauline: one who owed her father a fortune, another who boasted that he would kill a man to win her affections, and a third, Jimmie Dreen, whose coat button was found at the scene of the crime. The evidence points strongly to Jimmie, with whom Pauline is in love, until Pierre, Emil's servant, confesses that he killed his employer upon learning that he had lost his job. Much relieved, Pauline agrees to marry Jimmie.