Ben Macintyre, columnist for the Times (London) and author of Agent Zigzag: Lover, Traitor, Hero, Spy, named his top six true-life spy stories for the Times.
One book on the list:
Garbo: The Spy Who Saved D-Day by Mark Seaman
Juan Pujol, a Spanish anti-fascist codenamed “Garbo” by MI5, was a highly effective double agent.