The Double-Cross System in the War of 1939 to 1945,

If you have any interest in World War II spying, you need to hunt down a copy of this book. Written during the fall of 1945, this account of how England's collection of double agents fed false information to the German Abwehr is based directly on the document files of the Twenty Committee (the organization that "ran" the double agents), and is by one of the officers from that group. This book was originally written as an internal report, but fortunately Sir John (as he later became) kept a copy and was finally able to get it published. Surprisingly readable for an official report, this book is worth the effort of finding it.