Felix returns to Haberson. Upset over his altercation with Nell, he distracts himself by working on the Haberson Map and remembers his initial job interview with William, the CEO of Haberson. The interview consisted of one question: “What makes a perfect map?” (206). Felix’s answer—finding a map’s purpose by understanding its secrets—landed him the job.

Felix’s contemplations are interrupted by his coworkers, who encourage him to make up with Nell. William appears with a Haberson Map alert: a notice of Irene’s murder.

Nell awakens to find herself in the NYPL Map Division with Swann, Francis, Romi, and Eve. She learns that Wally attacked her and stole her bag, including Tam’s portfolio and Francis’s photo. The Cartographers reveal that they—and Wally, when he burglarized the library—used the Sanborn map to manifest the trap room in the Map Division. (Francis used a similar trick to disappear at Swann’s house earlier, and Romi’s shop also operates in a similar fashion.) This magical use of trap rooms on the old maps explains how Wally could enter and exit the NYPL undetected. Francis intended for the Sanborn map to protect Daniel from Wally, but it arrived too late. Nell finally believes Francis’s story about Agloe and realizes that Daniel’s reaction during the Junk Box Incident was meant to protect her from Wally, but she was just “too stubborn to listen” (215).