Jean-François and his friend Catherine both work in an advertising agency where a juicy contract with the Floc washing-machine is to be signed. But they quarrel and separate. Catherine joins a competing house while Jean-François goes on working on the Floc file. One day, the young man has a stroke of genius in deciding to tie in the Floc machine with the hit song "Les lavandières du Portugal" (The Washerwomen of Portugal)...