He was GARBO to the Allies and ALARIC to the Germans – the most successful double agent of the Second World War. Indeed, his spy network across Britain was so highly regarded that he was decorated for his achievements … by both sides.

Throughout the war, GARBO kept the Germans supplied with reports from his ring of twenty-four agents. Hitler's spymasters never discovered or even suspected a double-cross, but all the agents in GARBO's network existed solely in his imagination.

In one of the most daring espionage coups of all time, GARBO persuaded the enemy to hold back troops that might otherwise have defeated the Normandy landings on D-Day; without him, the Second World War could have taken a completely different course.

For decades, GARBO's true identity was a closely guarded secret. After the war, he vanished. Years later, after faking his own death, Juan Pujol García was persuaded by the author to emerge from the shadowy world of espionage, and in this new edition of his classic account, now updated to include his agents' original MI5 files, GARBO reveals his unique story.