It’s the middle of a hot, dusty St. Petersburg summer in the late 1860s. A doctor brings home a fancy box of chocolates for his wife and son—a strange gift on a scorching Saturday afternoon. Within an hour, both mother and child die an excruciating death, and the doctor is immediately arrested, suspected of poisoning. As investigator Porfiry Petrovich concedes, in such cases the obvious solution often turns out to be the correct solution. And in the city’s sweltering, oppressive atmosphere, even he lacks the energy to delve any deeper. But when additional, apparently unconnected, murders occur on the other side of town, a subtle and surprising pattern starts to emerge. Porfiry is forced to reassess his assumptions and follow a tenuous, uncertain trail that takes him into the hidden, squalid heart of the city and brings him face to face with incomprehensible horror and cruelty.