Daughter of Daniel and Tam, Nell is born into cartographic greatness and is raised by the Cartographers, partially in Agloe. This experience opens her mind to the fantastical possibilities of the magical realism of phantom settlements and trap rooms, though she later settles into the rigidity of cartographical science as she becomes an adult. She seems destined for success as she interns at the NYPL with her then-boyfriend Felix and earns the support of not just her father, Daniel, but also of Swann and Irene, the chair of the library. However, her fatal flaw is her hereditary stubbornness, which flares when she first discovers the Junk Box and realizes the value of the 1930 General Drafting New York road map within. Her argument with Daniel about its value results in her and Felix’s excommunication from the cartography industry, and her path continues to diverge from her father’s after that moment.

She finds a job at Classic making imaginative replicas of the ancient maps she once curated. Still dreaming of academic grandeur, she is ashamed of her perceived lowered status. However, she later rejects the opportunity to achieve her previous dreams of a career at the NYPL and passes up the possibility of a rekindled romance with Felix in favor of investigating the mystery of the Junk Box map.