November 1866: The grisly murder site in London's East End is thronged with onlookers. None of them expect the calmly efficient young woman among them to be a medical doctor, arrived to examine the corpse. Inspector Richard Tennant, overseeing the investigation, at first makes no effort to disguise his skepticism. But Dr. Julia Lewis is accustomed to such condescension . . .

To study medicine, Julia had to leave Britain, where universities still bar their doors to women, and travel to America. She returned home to work in her grandfather's practice—and to find London in the grip of a devastating cholera epidemic. In four years, however, she has seen nothing quite like this—a local clergyman's body sexually mutilated and displayed in a manner that she—and Tennant—both suspect is personal.

Days later, another body is found with links to the first, and Tennant calls in Dr. Lewis again. The murderer begins sending the police taunting letters and tantalizing clues—though the trail leads in multiple directions. Lewis and Tennant struggle to understand the killer's dark obsessions and motivations. But there is new urgency, for the doctor's role appears to have shifted from expert to target. And this killer is no impulsive monster, but a fiendishly calculating opponent, determined to see his plan through to its terrifying conclusion . . .