At the Café du Chat Noir, Joan Billaire, a dancer, attacks Mitzi for schooling her brother, Petit, in picking pockets and is saved from a knifing by Lupine, a thief. Later, Lupine enlists Petit's aid in a robbery, and the boy is accidentally wounded by him. Joan calls on Dr. Raoul de Boise, who informs the police; and when the boy dies, she is prevented from shooting Raoul by the intervention of Father Colomb. As Joan becomes romantically involved with the doctor, the jealous Lupine wounds Raoul. Joan confesses her part in robbing the church but is forced to marry Lupine as the price. Learning Raoul is alive, Lupine in a jealous rage confesses to killing Petit and is himself killed by the gendarmes.