Magic of Oz, The [The Wizard of Oz series #13]

In this witty and imaginative tale, the “Royal Historian of Oz,” L. Frank Baum, takes young readers back across The Great Sandy Desert for more exciting adventures in the wondrous Land of Oz. Old friends such as Dorothy, the Wizard, and the Cowardly Lion reappear, along with endearing new characters — the Glass Cat, the Hungry TiGerman, Little Trot, Cap’n Bill, the Lonesome Duck, and others.
Seeking special birthday presents to express their devotion to the wise and beautiful Princess Ozma, the friends venture beyond the Emerald City and into unknown territory. Little Trot and Cap’n Bill find themselves stuck — literally! — on an enchanted island, while Dorothy and the Wizard uncover a treasonous plot.