Content Warning: This guide includes graphic descriptions of violence against children, including murder, sexual assault, and bodily mutilation. It also includes references to the commercial sexual exploitation of children. Furthermore, because the novel is set in 1896, it includes dialogue that reflects the language of that era.

The date is January 8, 1919. The story’s narrator, identified in Chapter 2 as New York Times police reporter John Schuyler Moore, is having dinner at New York City’s famous Delmonico’s restaurant with his friend, the psychologist (or, in the language of the day, “alienist”) Laszlo Kreizler. Moore and Kreizler reflect on the life and recent death of their mutual friend, Theodore Roosevelt. Their conversation turns to the spring of 1896, when Roosevelt served as president of the city’s board of police commissioners. From March through June of that year, Moore and Kreizler, along with Roosevelt and a handful of others, helped track down a serial killer and put an end to the murderer’s grisly work. The details of the quarter-century-old case, including Kreizler’s controversial method of psychological profiling, have never been made public. Moore decides that it is now time to tell that story.