Nineteen-year-old Claude finds himself in a maximum-security prison to serve a 10-year sentence. Upon his arrival, he bumps heads with the hard-boiled Rousseau, a member of the Tarzan clan. When Claude finds that there is now a price on his head, he’s forced to accept protection from Ziz Grenier, the head of a rival clan. Claude makes friends with the transvestite Lucia and Jacques the Schizo, to whom he talks to about his girlfriend Karine, and his hopes of returning to her one day. The young man also becomes the friend of an old prisoner called the Phantom, who becomes his protector and spiritual guide.