At the heart of the deception was the 'Double Cross System', a team of double agents whose bravery, treachery, greed and inspiration succeeded in convincing the Nazis that Calais and Norway, not Normandy, were the targets of the 150,000-strong Allied invasion force. Under the direction of an eccentric but brilliant intelligence officer in tartan trousers, working from a smoky lair in St James's, these spies would weave a web of deception so intricate that it ensnared Hitler's army and helped to carry thousands of troops across the Channel in safety. These double agents were, variously, brave, treacherous, fickle, greedy and inspired. They were not conventional warriors, but their masterpiece of deceit saved countless lives. Their codenames were Bronx, Brutus, Treasure, Tricycle and Garbo. And this is their story.