[4] Dorothy Gale is gladly joining her Uncle Henry in California to visit relatives who live at Hugson's Ranch, after their vacation from Australia in Ozma of Oz.

Dorothy, Eureka (her cat) and Zeb are riding a buggy being pulled by a cab-horse named Jim when a violent earthquake strikes.

The Mangaboo people eventually drive the travelers out of their country into a dark tunnel, which leads to another kingdom.

After a close encounter with a family of baby dragons, they find themselves trapped in a cave with no exit.

Soon after renewing his acquaintance with the Emerald City staff and making the acquaintance of Ozma and her courtiers, the Wizard elects to remain in Oz permanently, planning to learn real magic from Glinda the good witch.

The others stay for an extended visit, whose highlights include a race between the wooden Saw-Horse and Jim, which the Sawhorse wins.

In fact, Baum accelerated this schedule, producing Dorothy and the Wizard in Oz only a year after the previous book.

The effect of this effort on the quality of the resulting work can only be a matter of speculation; but commentators have noted that this fourth Oz book is darker and more troubling than usual.

When Oz is finally reached, it is a bland "goody-goody place" with few positive events to offer.

This change is believed by some to be based on complaints from children as to how they didn't like the mention of the Wizard assisting Mombi, so Baum left this out of later books.