Using secret American, British and German sources previously unavailable, this story appears almost incredible. Few people know that behind all of the great decisions- and many of the small ones - of the past two world wars, lay information gathered from secret intelligence, either from agents or intercepted coded messages. At the time of writing the whole structure was still classified, yet Farago was able to obtain German records that had been lost for a generation, revealing a vast espionage network strung across Britain and the United States. He also shows how the Germans mopped up the British espionage network in 1939, and how it was painfully and carefully rebuilt by a new generation of British intelligence officers who cracked the German codes and fed false information to the Abwehr throughout the war, eventually contributing to the defeat of the Axis powers.