In a French prison, three men are coming to terms with the emotional and physical torment which their incarceration brings them. Arnaud is serving a six-month sentence for drug smuggling; he protests his innocence and will do anything to secure an early release. Francky is a hardened criminal who has all but lost his wife and family and who seeks comfort in self-inflicted abuse. Kader is in prison for theft; he is the most philosophical of the three men, he is growing accustomed to prison life and seems to prefer it to the world outside.

Trois détenus d'horizons sociaux différents se retrouvent dans la même cellule. Arnaud Grandjean, jeune étudiant issu d'un milieu aisé, va côtoyer durant six mois Francky, un braqueur condamné à dix ans de prison, et Kader, un délinquant multirécidiviste d'origine maghrébine, condamné à deux ans pour vol en flagrant délit. Pour ces trois hommes que seule la zonzon rapproche, la cohabitation va provoquer des confrontations indispensables pour comprendre ce qu'est la liberté.