The Wishing Horse of Oz (1935) is the twenty-ninth of the Oz books created by L. Frank Baum and the fifteenth written by Ruth Plumly Thompson. It was Illustrated by John R. Neill. This marked the point when Thompson had written more Oz books than Baum himself.
This Oz mystery starts in Skampavia where King Skamperoo wishes for a horse using enchanted emerald necklaces. When Chalk, the Wishing Horse of Oz falls from the sky, Skamperoo decides the emeralds must be from the Emerald City, and decides to conquer all of Oz.