The Shadow's Speed — L.W. Hewitt

As war engulfs Europe German archeologists uncover a mysterious energy source buried deep in a cave in the Swabian Alps. Desperate to reverse the tide of war back in Germany's favor, Reichsführer Heinrich Himmler orders the SS to turn the holenlicht into a weapon at any cost. The American OSS is equally determined to discover its secrets and avoid catastrophe for the Allied armies. A scientist's journal holds the only truth - and even decades later keeps the superpowers at bay as they race to discover its secrets.