To gain César's protection, which is worth having in what is a very dangerous environment, he must do a 'little job' for him - kill another inmate. From this point on he becomes César's property, while being haunted by his victim.
As the plot develops Malik starts to undertake more jobs for César during his 'good behaviour' release days. But César's influence is threatened when a number of the Corsicans are returned to Corsica, reducing his muscle, while a growing Muslim contingent in the prison is seen as a threat.
Meanwhile, Malik is far from stupid, and he has been developing his own interests.
This film has a very realistic feel about it. It won the Cannes Film Festival Grand Prix in 2009 and Best Film at the London Film Festival in the same year. It certainly paints a bleak picture of life inside this French prison.