Act 1 The scene is the house of Dr Petypon, a respectable middle-aged medical practitioner in Paris. His friend and colleague Dr Mongicourt calls and finds Petypon asleep on the floor. The two of them had been on the town celebrating a professional success and over-indulging at
Maxim's. Petypon wakes with a serious hangover and a strange young woman in his bed. She is
la Môme Crevette – roughly "the kid shrimp" – star dancer at the Moulin Rouge. His wife, Gabrielle, enters and finds la Môme's dress on the floor and takes it, assuming it is one she had ordered from her dressmaker. Thanks to a ruse by la Môme, Gabrielle leaves without suspecting anything, but la Môme now has no dress in which to leave the house. Mongicourt is sent to buy her one, but while he is away Petypon's uncle, General Petypon, calls. He has never met his nephew's wife, and assumes the young woman in Petypon's bed is Mme Petypon. He invites her, together with his nephew, to his country house. Petypon is aghast, but feels compelled to agree. The general departs, and Mongicourt arrives with a dress for la Môme, who leaves. Gabrielle returns, and her husband tells he is called away from town on a medical case. Two men deliver a new medical contraption for Petypon. It is an "ecstatic chair", designed to put a patient sitting in it into a euphoric trance. Left alone, Gabrielle opens the formal invitation delivered by the general, and concludes that though her husband is unable to join the general's house party, she can and will.
Act 2 At the general's château the provincial ladies are shocked but titillated by la Môme's free and easy behaviour and Parisian street-talk, including her catch phrase, "Eh! allez donc, c'est pas mon père!" ("Hey! come on, it's not my father!"), and they attempt to emulate her. Gabrielle arrives; when la Môme is introduced to her as "Madame Petypon" Gabrielle supposes her to be the general's wife. La Môme sings a rude song, which, fortunately, the ladies do not understand – though the general's army colleagues do – and then dances a can-can. Petypon grows increasingly frantic. Corignon, fiancé of the general's niece, arrives. He is an old flame of la Môme, and they run away from the château together. Petypon pleads an urgent medical summons and departs for Paris.
Act 3 Back chez Petypon, the mistaken identities proliferate, and characters are frozen in mid-action at crucial moments by sitting in the ecstatic chair. An amorous young duke lusting after "Mme Petypon" (la Môme) finds himself in the embrace of a rampaging Gabrielle. There is a chase scene, much slapping of faces, and a threatened duel is narrowly avoided. Eventually the truth emerges, along with a reasonably plausible innocent explanation of the various impersonations, and everyone ends up with the appropriate partner, including the general and la Môme who go off affectionately together: she tells the assembled company, "Eh! allez donc, c'est pas mon père!". ==Reception==