A house in Paris happens to have two families living there with the same last name. In one apartment lives opera singer Gambetta Duval with his two daughters, Jeanne and Nita. In the second apartment lives old lady Duval with her grandchild Philippa and an her lodger, the physician Leon Monnier. Jeanne is secretly in love with Dr. Monnier who is secretly in love with Nita, who is secretly having an affair with the great playwright Armand de Marny.