This grim and claustrophobic drama chronicles the lives of the prisoners in Colditz Castle from the arrival of the first British prisoners after Dunkirk until the liberation of the castle by the Americans in 1945. Colditz was a "special" camp, designed by the Nazis to hold high-risk and politically important prisoners. Many of the series' plots are based on real events.
The war slowly comes to an end, with the allied prisoners and the Germans gradually forming a united front against threats from the advancing Russian army and the SS. The castle is bombed by allied forces who are not aware of its true nature, and all the inhabitants gather together in the cellars with this threat drawing them closer together.