The little band is Cat, Fouad, Antoine and Sami, four 12-year-old schoolboys. Out of pride and provocation, they embark on a crazy project: to blow up the factory that has been polluting their river for years. But in the newly formed group, disagreements are frequent and tie votes constantly paralyze the action. To decide between themselves, they then decide to bring Aimé, a rejected and lonely kid, into their little band. As excited as they are distraught by the magnitude of their mission, the five accomplices will learn to live and fight together in this funny and uncertain adventure that will totally surpass them.