It's the summer of 1888 and a bizarre killer is stalking the gas-lit streets of New York. But are the murders a case of black magic—or simple blackmail? From the high-class gambling dens of the Tenderloin to the glittering mansions of Fifth Avenue, consulting detective Harrison Fearing Pell follows a twisted trail of lies, treachery and madness that might end much closer to home than she ever imagined.