This is a story you know, right? It’s early in the war and western Europe has fallen. Only the Channel stands between Britain and the fascist yoke; only Atlantic shipping lanes offer hope of the population continuing to be fed, clothed and armed. But hunting “wolf packs” of Nazi U-boats pick off merchant shipping at will, coordinated by radio instructions the Brits can intercept but can’t read, thanks to the fiendish Enigma encryption machine. Unless something is done – and fast – Hitler’s plan to first bomb, then starve the country will succeed. Enter the genius Alan Turing, working as...