The young and charming Mandoline, accountant of the advertising agency Publi-Pub, has stolen documents proving that the company kept double accounts. Remorseful when she wanted to pass this evidence to a tax inspector, she decides to put the documents back in the agency's safe, but does not really know how to go about it. Her friend Marie-Charlotte, a transvestite, helps him find a young safe-drilling man in his condition, who will help him open the safe - but of course, the matter is not so simple.