Les Maîtres-nageurs (1951)

A married industrialist maintains three mistresses. On the instructions of his wife, the tax inspector seizes the small notebook where he records his illegal dealings. After a stormy marital explanation, the industrialist decides to reduce his costs by getting rid of his mistresses and expresses the intention of returning to legality. But he realizes that everyone, even his wife, prefers the old situation, fraud and mistresses, thanks to which everyone found his little profit.