This brief chapter gives an overview of the moral climate of Chicago in the late 1800s, describing the influx of people, particularly single young women. Chicago's declining moral fabric is established through portrayal of the mass of nightclubs and brothels, along with changing social norms. Chapter 1 also notes the frequency of deaths in Chicago during that time, with train accidents, fires, disease, and murder among the deadly means At the end of Chapter 1, doctor, pharmacist, and serial killer H.H. Holmes (given birth name: Herman Webster Mudgett) enters the scene as the novel's antagonist.
One function of this chapter is to introduce the other main character, H. H. Holmes, and his connection to the setting. Chapter 1 provides more insight into the setting: Chicago at the end of the Guilded Age. Larson sets the mood for a morally declining Chicago to show the appeal of the city for someone like Holmes. A place where murder and crime are frequent and where conservative social norms are being questioned, and sometimes ignored, is certainly alluring for a vile character like Holmes.
In this chapter, note Larson's use of the word "disappear." The word is used as a double entendre and foreshadows later events in the novel. Larson describes Chicago, in this time period, as a place where one could easily and literally "disappear" forever, fallen victim to accident, disease, or murder. The notion of disappearing also serves as a symbol for Holmes's ability to figuratively "disappear" in Chicago, going virtually unnoticed in a spree of murders. Chapter 1 focuses on the theme of evil, one that will be carried throughout the book, particularly in scenes where Holmes is featured.