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 Emerald City to find out who is behind the poisoning.
Tilly Pages and her friend Oskar journey to Washington, D.C., where she wanders inside the books at the Library of Congress and they try to stop a nefarious plan with some powerful help.