On June 6, 1944, 150,000 Allied troops landed on the beaches of Normandy and suffered an astonishingly low rate of casualties. A stunning military accomplishment, it was also a masterpiece of trickery. Operation Fortitude, which protected and enabled the invasion, and the Double Cross system, which specialized in turning German spies into double agents, tricked the Nazis into believing that the Allied attacks would come in Calais and Norway rather than Normandy. It was the most sophisticated and successful deception operation ever carried out, ensuring Allied victory at the most pivotal point in the war. This epic event has never before been told from the perspective of the key individuals in the Double Cross system, until now. Together they made up one of the oddest and most brilliant military units ever assembled.