It was the most important submarine capture of WWII, yet it remained a secret known only to a handful of men and the black waters of the Atlantic until long after the war was over. In the early days of WWII, Admiral Doenitz's deadly U-Boat fleet and their stealthy "wolfpack" attacks devastated Allied shipping. The success of Doenitz's strategy relied on the complex codes generated by the legendary Enigma machine, which rendered German radio transmissions indecipherable. But when the crew of U-110 was unable to scuttle their vessel as ordered, the sub along with the vital Enigma machine and its codebooks was captured by the Allies, and the tide of the conflict turned. Here, the incredible tale of U-110 is told through rare archival footage and photos, captured documents, and interviews with German and British sailors. Admiral Doenitz's journals reveal how the Nazis never suspected that their codes had been broken, while cryptologists demonstrate why the only way to break Enigma was to capture one of the machines.