1927, Breslau, Poland: Two elaborate and sadistic murders are discovered within days of each other. The body of an unknown musician, bound and gagged, is found in the walls of a shoemaker's workshop--he's been sealed in alive. Elsewhere in the city, the mutilated body of a locksmith is found. Next to each victim is a torn-out calendar page, with the day of the death marked in blood. Nothing else seems to connect the cases. It falls to Criminal Councilor Eberhard Mock to uncover the link, the mystery taking him deep into the Breslau underground, a scene of bars and bordellos so sordid as to be nearly supernatural, and where seedy aristocrats trade in valuable information...and where, it becomes clear, a serial killer lurks. Meanwhile, Mock's own hard-drinking nocturnal habits soon threaten his volatile marriage, and prompt some strange behavior from his young wife...and before long, his team will be investigating not only two of the grisliest murders in the city's history, but Mock's own wife.