During World War II, the German army used Colditz Castle to hold the most defiant Allied soldiers, and for four years, these prisoners of the castle tested its walls and its guards with ingenious escape attempts that would become legend. Much as he did in Agent Zigzag, Ben Macintyre digs below the surface of a familiar story, and here he introduces some of Colditz's intriguing characters: an Indian doctor on a hunger strike, a British inventor aiding escapees, and Florimond Duke—America's oldest paratrooper and least successful secret agent.