Colditz Castle sits on a cliff above the German town of the same name, and the Nazis chose it for a reason: they believed no one could get out. The programme, part of the Secrets of World War II series, tells the story of the officers held there, many of them repeat escapees transferred in from other camps precisely because they had already broken out once. It walks through the camp's tunnels, forged documents, and homemade disguises, and the glider built in secret in an attic loft, never flown but never discovered either. Interviews and archival photographs trace how prisoners exploited blind spots in the guards' routines and how the Germans kept adapting security in response. The film treats the castle less as a building than as a running contest of nerve and ingenuity between captors and captives, and it lays out which escape plans worked, which failed, and what happened to the men who tried them.