At the end of World War II, the Cabinet Office commissioned an eminent academic, Professor William Mackenzie, to undertake a comprehensive secret history of Special Operations Executive. Given access to both personnel and the surviving wartime files, Mackenzie's report was a reference document to be used by intelligence agencies in a future conflict, its audience the very elite of Whitehall insiders. Now, this highly classified account has been made available. Never before have SOE's operations across the world been described in such detail and with total authority. Mackenzie's document explores numerous controversies and reveals dozens of previously undisclosed episodes from Britain's secret war against the Axis. Who were the agents parachuted in Germany? What became of schemes designed to protect Gibraltar from a Spanish invasion? When did SOE decide to collaborate with the NKVD and infiltrate Soviet spies into Eastern Europe? These and other wartime mysteries are packed into one of the most controversial documents of our time.