Friends Ojo and Button-Bright are wandering along the border between the Gillikin and Winkie countries of Oz. They meet Ugu the Shoemaker, still in the form of a gray dove that he acquired at the end of The Lost Princess of Oz. Ugu is searching for a mysterious item called the Ring of Time; still conscience-stricken over his earlier actions, Ugu wants to go back in time to persuade his earlier self to avoid evil plots and vain ambitions.
As they talk about matters Ozian, Button-Bright wishes that he could go back in time to witness the enchantment of Oz by the fairy queen Lurline. He suddenly disappears, and his two companions realize that he'd been sitting in the Ring of Time (a humble circle of tree roots) all along. They quickly follow him into the past, though are unable to locate him. (Button-Bright is lost again.)
The boys are thus launched on separate adventures. Button-Bright falls in with a group of Yookoohoos in the Gillikin Country, and witnesses the wedding of the Yoop with Mrs. Yoop and their transformation into giants. Ojo and Ugu see the fairy court of Queen Lurline float in on a cloud, and learn how Lurline uses Magic Eggs from the legendary phoenix to create a full-blown fairyland out of the already magical Oz. The fairies return Ugu to his human form; at the Winkie city of Herku, the repentant man from the future ("gray Ugu") confronts his earlier self ("yellow Ugu"), who proves to be resistant to persuasion. A ferociously tangled conjunction of Yoops, giants, Yookoohoos, and Herku citizens is eventually sorted out by Lurline, to produce a new order that will evolve into the Oz familiar to all Ozophiles to come.
In the process, Ojo accidentally swallows a Magic Egg and becomes a powerful magical entity himself, much to his own distress. He goes to the Land of An, deep in the Forest of Burzee, for a course of instruction on controlling it.
Author Dana draws upon many details in the works of L. Frank Baum to expand, develop, and expound upon aspects of the Oz mythos. He provides background on the Yookoohoos and origins for the city of Herku and the Yoops, and explains how Princess Ozma matures from an infant to a young girl while other people in Oz do not age, among other matters. He generates an intricate and cleverly-woven web of satisfying speculation on the grand narrative of Oz.