World War I. German ace pilot Captain von Rauffenstein shoots down the plane of aristocratic French pilot Captain de Boeldieu and his mechanic co-pilot. The captured officers befriend Lieutenant Rosenthal, a former Jewish banker, in the Hallbach POW camp. They plan an escape, but are transferred to the heavily guarded Wintersborn fortress prison in Alsace, overseen by von Rauffenstein.

The Grand Illusion
Two French soldiers, held captive in a German POW camp, use their resourcefulness and perseverance to orchestrate bold escape attempts, but are ultimately relocated to a heavily fortified prison that appears insurmountable.