Occupied Breslau, 1933: Two women are found murdered on a train with scorpions writhing on their bodies and an indecipherable note in an apparently oriental language nearby. Police Inspector Eberhard Mock is called to investigate, but uncovering the truth in Breslau is no straightforward matter. The city is in the grip of the Gestapo, and the mysterious note seems to indicate a ritual killing with roots in the Crusades.