Breslau 1933: the mutilated bodies of a young woman and her ladies" maid are found on a train - scorpions writhe in their slashed stomach. Inspector Eberhard Mock is called in to deal with the case, and is assigned an assistant, Herbert Anwaldt, an orphan. The investigation leads them deep into the city's underbelly. As Mock and Anwaldt unravel a mystery of ritual killing that dates back to the time of the Crusades, the elderly Mock and the young, fatherless Anwaldt become close. But the dark, occult aspect of this macabre case might prove too much for Anwaldt's sanity.