Occupied Breslau, 1933: Two young women are found murdered on a train, scorpions writhing on their bodies, an indecipherable note in an apparently oriental language nearby ... Police Inspector Eberhard Mock is called to investigate. But uncovering the truth is no straightforward matter in Breslau. The city is in the grip of the Gestapo, and has become a place where spies are everywhere, corrupt ministers torture confessions from Jewish merchants, and Freemasons guard their secrets with blackmail and violence. As Mock and his young assistant Herbert Anwaldt plunge into the city's squalid underbelly the case takes on a dark twist of the occult when the mysterious note seems to indicate a ritual killing with roots in the Crusades.