This drama depicts the misery of neglected children in big cities. 13 years old Bruno is of a good family, but since the death of his grandmother he spends most of his time alone, in a phantasy world, while his mother is away at work. But then he befriends the violent Jean-Roger, who's from a severely disturbed family, where nobody cares what he's doing. In school Jean-Roger drives their teacher into despair just for fun. To separate the two boys, she starts to stimulate Bruno's interests by giving him extra lessons. When Jean-Roger fears loosing his one and only friend, he becomes even more aggressive.
A bunch of crooked cops raid a ruined building located in an impoverished suburb of Paris, determined to furiously avenge the death of one of them, murdered by the ruthless criminal gang hidden on top of the dark labyrinth that will become a deathly trap when the living, unexpectedly turned into the undead by a mysterious plague, begin to devour the world.