A group of French soldiers, including the patrician Captain de Boeldieu (Pierre Fresnay) and the working-class Lieutenant Maréchal (Jean Gabin), 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 (Erich von Stroheim), who has formed an unexpected bond with de Boeldieu.