An edited collection of peer-reviewed articles using newly-released sources - British, German and Italian - integrated to form a fascinating narrative of the intelligence-led fight of the British Secret Service in the existential struggle with Nazi Germany. The main sections are: British Secret Warfare and the Nazi Challenge; Counter-Intelligence Against Axis Spies; and Hugh Trevor-Roper and Secret Service. An inside and authentic story with original and little-known but vital themes including the British Military Mission to Poland, the British Special Operations Executive (SOE) in Poland, British subversion in French East Africa, 'on secret service for the Duce', British Radio Intelligence, and J C Masterman and the Security Service. This is a uniquely human story of survival with all the drama of power struggles, personality clashes, errors, heroism, human intelligence.