Wanner, a man of independent means, has a mistress in Geneva. However, in order to spend a few days with her without risk, he decides to open a sales branch of a long-defunct company. He therefore hires a "trusted" employee in Geneva to look after the office premises, including the bedroom, and to provide his mistress with everything she needs. This arrangement works quite well at first, and Wanner enjoys this sweet diversion to the fullest until... well, until his wife wants to visit the branch and, above all, meet his business partner. Where can he conjure up a partner so quickly?