Jean-François Robignac, a teacher, arrives at a provincial college to teach literature to ninth-graders. He quickly wins over the children with his youthful way with words. But his parents want to have him expelled when they learn that Jean-François uses slang words to rejuvenate writers' texts.

Pépito runs a gang of thugs with authority. He has a natural son, Gaston, a professor of literature in Aix-en-Provence, whom he has hardly ever seen. Gaston announces himself for Christmas, and Pépito decides to make him look good by moving into his headquarters: a château where the crooks will be able to exercise their talents as composers.