Dorothy Gale, after her adventures in Oz, arrives at Hugson's Siding in California, where she meets Zeb, a boy working on a nearby ranch. They are soon caught in a series of earthquakes that cause their horse, Jim, to fall into a crack in the earth, pulling them along with him. They find themselves in a colorful underground world filled with strange lights and creatures. As they float downwards, they encounter a talking horse named Jim and a kitten named Eureka, who can also speak. They eventually land in a vibrant city inhabited by the Mangaboos, who are vegetable people. The Mangaboos mistake them for the cause of a recent disaster, the "Rain of Stones," and take them to the Sorcerer Gwig, who is not pleased with their presence. The group is led to the House of the Sorcerer, where they meet Gwig, who challenges the Wizard to prove his worth. The Wizard performs tricks, but Gwig is not impressed. After a series of events, including a confrontation with the Sorcerer, the group escapes and continues their journey through the underground world. They eventually reach the Valley of Voe, where they meet invisible inhabitants who explain their way of life and the dangers of the bears that roam the valley. The group learns to walk on water to escape the bears and continues their journey, eventually reaching the Pyramid Mountain. After a series of trials, including a confrontation with the Gargoyles, they find themselves in a cave where they must wait for Ozma, the ruler of Oz, to help them return home. The Wizard devises a plan to use the Magic Belt to wish them back to Kansas. In the end, Dorothy and her friends are returned to the surface, where they reunite with their loved ones. Zeb expresses his gratitude for the adventures they shared, and they all reflect on the wonders of their journey through the magical land beneath the earth.
By L. Frank Baum · First published 1908 · Genre: Fantasy, Adventure, Children's Literature · 20 chapters