Content Warning: This section includes references to graphic descriptions of violence against children and the commercial sexual exploitation of children. Furthermore, because the novel is set in 1896, it includes dialogue that reflects the language of that era.

Dr. Laszlo Kreizler is the book’s title character, an alienist who leads a clandestine search for a serial killer. In the 19th century, doctors who treated patients with mental illness were called “alienists,” and the patients themselves were called “aliens.” Throughout most of this period, treatment consisted of little more than keeping patients sedated and isolated from the general population (Bhugra, Dinesh, and Susham Gupta. “Alienist in the 21st Century.” Asian Journal of Psychiatry, 4(2):92-5, June 2011). Kreizler is depicted as a man ahead of his time—as controversial in the field of medicine as he is in that of crime solving—and as such his theories and practices have more in common with those of a 20th-century Freudian psychoanalyst than a typical 19th-century alienist. Kreizler subscribes to a theory of individual psychological context, which holds that childhood experiences, particularly traumatic experiences “concealed by the family structure,” shape perceptions and behavior in adulthood (301).