A group of young pacifists from Brittany is taken to a camp destined to deserters. They end up by accepting the increasing violence with which they are trained, and become true killing machines. In April, 1961, they are moved to the Aurès mountains in Algeria where they face off against troops from the National Liberation Army (Algeria). During the battle, the battalion captures a rebel fighter which they shall execute the next morning. Their most precious ideals are supposed to become overridden by sheer discipline.