Doctor Moulineaux begins a clandestine affair with Suzanne, one of his patients.
To conceal his adulterous passion, he rents a mezzanine floor formerly occupied by a seamstress. Barely settled in with his mistress,
Moulineaux soon finds himself confronted by the arrival of some of the dressmaker's customers, as well as his mother-in-law, his lawful wife and Suzanne's husband, who also comes with his mistress...