While some of the characters and events are fictional, the book is based on the real-life attempt by the Allies to use British intelligence to cover up the true plans for D-Day.

[4] The German spy Catherine Blake, whose real name is Anna von Steiner, an Abwehr operative, actually is close to learning the secret.

The basic idea of it is that after uncovering the German spy Catherine Blake, instead of capturing and imprisoning her, the British Intelligence provides her with false documents which she accepts as information she seeks.

If she could have fled she would be able to tell all she knew about British Intelligence agents and their Double Cross operation, and maybe Germans would understand that they had been deceived all the time.

[citation needed] Scott Veale, writing for the New York Times, called the book a "strictly a connect-the-dots adventure" and criticised its length and style.