Eleven-year-old Tilly Pages, who has found comfort in her grandparents' bookshop since her mother's disappearance, now learns that she can bookwander into any stories, and decides to seek her mother.
When Milo's uncle and Tilly's grandfather are poisoned by a mysterious copy of The Wizard of Oz and fall into a deep sleep, Milo and Tilly travel to the Emard City to find out who is behind the poisoning.