What if History were written by the defeated?

Historian Zara Rose is hired to investigate the discovery of an undamaged German U-boat in the North Sea. There she discovers Die Fledermaus, a Nazi superweapon powered by an unstable black matter, capable of transporting its passengers through time.

After accidentally triggering the device, Zara travels to the past where she meets the mysterious Der Meister, a physicist who created the weapon. When a colleague vanishes with the device, Zara and her fellow historian Stefan Krause help a shadowy agency apprehend the thief.

In the wrong hand the device could rewrite history or kill countless millions. Can Zara find Die Fledermaus before Der Meister's visions of a renewed Third Reich can be brought to its terrible fruition?