Shortly before noon on June 4, 1944, the sonar operator on a destroyer prowling off the coast of West Africa heard a sharp, metallic ping. The sound could mean only one thing: The German submarine that their hunter-killer group had been tracking, U-505, was lurking somewhere below. The ensuing struggle between exhausted hunter and venomous prey would make history when American sailors boarded an enemy warship at sea for the first time since the War of 1812.

That day's victory was the culmination of an unrelenting campaign against the Nazi submarine threat by the U.S. Navy's "Tenth Fleet"--a mysterious unit that could predict the locations and movement of Hitler's U-boats. Run by Commander Kenneth Knowles, Tenth Fleet had guided Captain Dan Gallery to U-505; to repay the favor, Gallery was going to steal an Enigma machine for him.

Now all they had to do was to make an entire U-boat, its crew, and its secrets vanish into thin air . . .

In this swashbuckling adventure story, bestselling historian Alexander Rose draws on long-classified encrypted documents and intercepted German transmissions to reveal in full, for the first time, how an owlish egghead and a glory-seeking buccaneer teamed up to score the richest prize on the high seas.