Three members of the Communist Party assassinate a German officer during World War II. Germany responds with an order to execute 150 prisoners of war. One of the men to be executed is seventeen-year-old Guy Môquet, whose eventual death becomes one of the symbols of the French rebellion against the German occupation. The film depicts the events from the moment immediately preceding the assassination to the execution itself in 1941. The director shows not only the point of view of the sentenced men, but he also describes the obedience of the German leaders without any defence.