Eddie Chapman was a charming criminal, a con man, and a philanderer. He was also one of the most remarkable double agents Britain has ever produced. In 1941, after training as a German spy in occupied France, Chapman was parachuted into Britain with orders to blow up an airplane factory. Instead, he contacted MI5, the British Secret Service. For the next four years, he worked as a double agent, a British spy at the heart of the German Secret Service. Crisscrossing Europe under different names, weaving plans, spreading disinformation, and miraculously keeping his stories straight under intense interrogation, he even managed to gain some profit and seduce beautiful women along the way. MI5 has now declassified all of Chapman's files, allowing the full story to be told, a unique glimpse into the psychology of espionage, with its thin and shifting line between fidelity and betrayal.