Augustin Robustal and his wife Lilane run the riverside café "Au joyeux gardon" and if the "gardon" (roach) is happy, the owners of the establishment are not as business is bad. Indeed the place is almost deserted except by four faithful patrons, Francis, a garage owner, Pivois, a man with a modest private income, Loulou, a radio technician and Boudoux, an undertaker. Now, the Robustals employ a fanciful but gifted waiter, Hippolyte. This one happens to be infatuated with Liliane, so much so that one day he takes out a life insurance in her favor. The four regulars' reaction is instant: they offer Robustal to execute Hippolyte, in exchange for a commission.