In turn-of-the-century France, Dr. Petypon, a young surgeon, goes out for a night of drinking with his good friend Mongicourt, only to awaken the next morning to find that he has brought home with him a young dancer known as "La Mome," The Shrimp. He is forced to hide the girl until his wife, who is much older than he, leaves the house. Before he can get the dancer away, however, his uncle, a general arrives and finds La Mome in his nephew's bed. Never having met the real Madame Petypon, the general assumes that La Mome is Petypon's wife. Dr. Petypon is too embarrassed to admit the truth to his relative, so he allows the deception to continue, only to be invited by his uncle to a family gathering, an invitation which he is forced to accept for himself and his "wife." After the general leaves, Petypon sends the dancer on her way, just as the real Madame Petypon returns. Petypon then tells his wife that he must leave town on business, and rushes back to Maxim's to get the dancer and go to his uncle's. In the meantime, Madame Petypon receives a written invitation to the family affair, and, believing her husband is out of town, decides to attend on her own. At the general's house, all believe that La Mome is truly Petypon's wife, and that the real Madame Petypon is simply a strange, uninvited guest. Despite the presence of his two "wives," Petypon muddles through the gathering until it is announced that Corignon, a young officer engaged to the general's niece, has run off with La Mome, who was his former girl friend. The guests all take pity on Dr. Petypon, believing he has been abandoned by his wife. Now Madame Petypon, who believes that La Mome is really her husband's mistress, announces her intention to obtain a divorce. A duel is arranged between the bridegroom and Petypon in order "to defend the family honor." Petypon is saved from both the duel and his wife by La Mome, who tells all that Petypon knew that she was the Corignon's former lover, and simply had her pretend to be Madame Petypon in an attempt to avoid a family scandal.
