After publishing an acclaimed biography of Jean Moulin, leader of the French Resistance, Patrick Marnham received an anonymous letter from a person who claimed to have worked for British Intelligence during the war. The ex-spy praised his book but insisted that he had missed the real 'treasure'. The letter drew Marnham back to the early 1960s when he had been taught French by a mercurial woman - a former Resistance leader, whose SOE network was broken on the same day that Moulin was captured and who endured eighteen months in Ravensbru ck concentration camp. Could these two events have been connected? His anonymous correspondent offered a tantalising set of clues that seemed to implicate Churchill and British Intelligence in the catastrophe.

Drawing on a deep knowledge of France and original research in British and French archives, War in the Shadows exposes the ruthless double-dealing of the Allied intelligence services and the Gestapo through one of the darkest periods of the Second World War. It is a story worthy of Le Carre, but with this difference - it is not fiction.