The year is 1919. World War I has ended. But one man – Karl Donitz – is not focused on peace. A veteran of Germany’s WWI submarines, Donitz is being held in a British prison. Awaiting release, he is already imagining another war – a war he believes Germany can decisively win. The key will be the German “Untersee Boot” or “U-boat.” Analyzing U-boat performance in World War I, Donitz believes Germany could have won – if they had had more submarines.