While Burnham and his associates contemplate fair sites, Holmes's success as a pharmacist and business owner continues to flourish. Holmes travels to Minneapolis because he cannot take his mind off Myrta Z. Belknap, a beautiful, voluptuous, blond woman he had met in a prior trip there. He convinces Myrta to let him court her. After Holmes's multiple trips to Minneapolis, and despite his unconventional courting practices, Myrta agrees to marry him, justifying his unconventional ways as Chicago convention. Holmes brings Myrta back to Chicago. At first, Myrta is enamored with Chicago and Holmes. However, her reverie is soon broken as she begins to grow jealous of the attention that Holmes gets from female customers in the drugstore. She grows more and more withdrawn and depressed and writes letters to her parents. By 1888, her parents move to Wilmette, Illinois. Soon after, Myrta moves in with them and has a child, Lucy, fathered by Holmes. Holmes visits Myrta and Lucy sporadically, excusing his long absences with his busy work schedule.
Meanwhile, Holmes buys the land across the street from the drugstore in Englewood and concocts an elaborate plan to design a building that would house his pharmacy and other businesses on the first floor, with the remaining two upper floors left for his living space and apartments for rent. He refuses to hire an architect because his secret plans would be revealed: an airtight vault equipped with gas valve, chute from the upper floors to the basement, and subcompartments below the basement. Instead, Holmes designs the building himself and contracts out several workers to complete the construction, frequently firing workers or driving them to quit in an effort to keep knowledge of the building design to a minimum. However, in the midst of construction, Holmes develops a few friendships that become important to him later. Amongst them is alcoholic, married father of five, and carpenter, Benjamin Pietzel. Albeit slow, the construction is finally complete mid-year 1890. Claiming there will be no market competition, Holmes sells the old store to an unsuspecting person. Holmes fills the businesses on the first floor, some being self-created enterprises with fictitious owners, to dodge those attempting to collect debts.
To Holmes's pure satisfaction, Jackson Park is named the official fair site in November. With the glory of this announcement, Holmes begins his plan to partake in yet another building project.
This chapter travels deeper into the mind of serial killer H.H. Holmes, where truly evil and psychopathic tendencies lurk. Before this, the novel identifies Holmes as a killer. In Chapter 5, the reader gets into the deviant's head a little more. For example, Holmes doesn't hesitate to do what it takes to conceal the purpose of his building design despite the fact he has to tamper with peoples' livelihoods to do so. Holmes shows an ability to manipulate those around him to get what he wants and to keep his reputation solid. Larson also uses an allusion to Jack the Ripper, famous London serial killer of the time, to give a comparison point for Holmes's evil. In the characterization of Holmes's interactions with others, Larson spreads the theme of evil throughout this chapter.
Chapter 5 helps advance the plot in several ways. For one, the reader is briefly introduced to several characters, people who are integral to Holmes's exploitation and destruction of others, particularly the young women who cross his path. Benjamin Pietzel becomes an increasingly important character later in the novel.