Amazing movie by the same director of 'The beat that my heart skipped' (De battre mon coeur s'est arrêté).
A 19 year old arabic man is put in jail for agressing a policeman. Most of the movie is his 'education' process to turn into a big criminal. His first crime - the assassination of another prisoner - is a quite strong scene, where he hides a razor blade in his mounth and the execution way less clean than he planned. He, then, gradually gets more protection from the big corsican mobster that rules the prison.
A really interesting feature of this film is the care the director took in making the protagonist to be perceived as someone the audience can 'like', given the crimes he is commiting. His conciliation with the arabic origins and his relationship with his dying friend and family ane used to that effect.