The evil Nome King is determined to recover the Magic Belt from Ozma, ruler of Oz. He plans to tunnel under the Deadly Desert that surrounds Oz, to emerge in the Emerald City and lay waste to it and the land around it. Meanwhile, Dorothy has moved to Oz with her Uncle Henry and Auntie Em after life got hard in Kansas. They tour the land, having entertaining adventures, and return to the Emerald City just as the armies of the Nome King are beginning their final assault.