During WWI, three French officers are captured. Captain De Boeldieu is an aristocrat while Lieutenant Marechal was a mechanic in civilian life. They meet other prisoners from various backgrounds, as Rosenthal, son of wealthy Jewish bankers. They are separated from Rosenthal before managing to escape. A few months later, they meet again in a fortress commanded by the aristocrat Van Rauffenstein. De Boeldieu strikes up a friendship with him but Marechal and Rosenthal still want to escape...

One of the very first prison escape movies, La Grande Illusion is hailed as one of the greatest films ever made.