The true story of decrypting the Nazis' secret codes and turning the tide of World War II.

Autumn, 1931. An employee of the German code department sells French counterintelligence agents an astonishing secret. So begins a ten-year battle to break the most abstract and complex encryption machines ever invented. From Poland under siege to the English countryside, the Swiss mountains to the hold of a u-boat, a mad pursuit ensues down a maze of digits, letters, and betrayals.