Rene, the Vicomte de St. Denis, returns to Paris from a hunting trip in Africa before his fiancée Louise expects him and makes dates with Paulette de l'Enclos at ten, Suzanne at twelve and Gabrielle at one a.m. He forgets all three, however, when he finds an abandoned baby in his car. The next morning, Max de l'Enclos, a friend of Rene, visits with his new wife, who is none other than Paulette. All is chaos when, as Rene and his valet, Victor, give "Monsieur Baby" a bath, Gabrielle arrives demanding an explanation, and a nurse, Sally, reports for duty. While Victor gives Rene a shave, he discovers Rene's third woman is his own wife Suzanne and threatens to quit. The real hired nurse then arrives, and Sally confesses she is an out-of-work performer from America. Rene hires her anyway and that night, stays in with her and "Monsieur Baby," whom Sally names Robin, and contemplates family life with Louise. When Rene arrives late to a house party at Louise's chateau in the country with nurse and baby in tow, the guests laugh and Louise's father insults Rene. That night, after Louise breaks the engagement, telling Rene they never loved each other, Rene tells Sally how happy he is. Later Paulette visits Rene in his room at the chateau, begging him to be more discreet with the inscribed cigarette case she gave him, and Sally becomes jealous. When Max demands to see his wife, Sally hides with Paulette, who has fainted, behind a curtain. To get rid of Max, Rene pulls the curtain just enough to reveal Sally's blonde hair. Furious, Sally leaves with Robin to return to Paris, and Rene follows, returning home to find the poor couple who had abandoned the child. After learning that Robin was an orphan left in the couple's care, and that the couple has six children of their own, Rene pays them 10,000 francs for Robin. Rene then gives Sally Paulette's cigarette case to discard and they kiss.