One December night in 1942, a Nazi parachutist landed in a Cambridgeshire field. His mission - to sabotage the British war effort. His name was Eddie Chapman, but he would shortly become MI5's Agent Zigzag. Dashing and louche, courageous and unpredictable, the traitor was a patriot inside, and the villain a hero. The problem for Chapman, his many lovers and his spymasters was knowing who he was. Ben Macintyre weaves together diaries, letters, photographs, memories and MI5 files to create the account of Britain's double agent.