The film shows the seizure of power by the Nazis and Hitler wants a trial, at a time when France has just declared war on Germany (Sept. 3, 1939). Hybrid composition, it alternates originals and reconstructions performed by actors (docudrama). A not-so-subtle condemnation of Hitler, Nazism and Germany by the movie's French film makers, which conveniently makes no mention of how the policies of Great Britain and France created Hitler and allowed him to go as far as he did prior to the beginning of the Second World War.

A group of French soldiers, including the patrician Captain de Boeldieu and the working-class Lieutenant Maréchal, grapple with their own class differences after being captured and held in a World War I German prison camp. When the men are transferred to a high-security fortress, they must concoct a plan to escape beneath the watchful eye of aristocratic German officer von Rauffenstein, who has formed an unexpected bond with de Boeldieu.