The Giant Horse of Oz is the twenty-second in the series of Oz books created by L. Frank Baum and his successors. The book is set in the tiny kingdom of the Ozure Isles in the remote region of Munchkin Land in Oz. The story begins with the evil witch Mombi kidnapping Queen Orin and leaving a fire-breathing lake monster, Quiberon, to imprison the natives. As the situation worsens, Quiberon demands a mortal maiden for company, targeting three American girls in the Emerald City: Dorothy Gale, Betsy Bobbin, and Trot.