L. Frank Baum 
Tik-Tok of Oz 

The eigth book in L. Frank Baums beloved Oz series, Tik-Tok of Oz finds a the young Betsy Bobbin and her trusty mule, Hank, magically transported from Oklahoma to the same fantastical world once visited by Dorothy Gale. In Oz, Betsy befriends the kindly, old Shaggy Man, and agrees to help him search for his missing brother in the Nome Kingdom. Joined by the mechanical man, Tik-Tok, and a cast of colorful characters, Betsy and Shaggy Man soon find themselves dealing with a much bigger problem: trying to prevent a war between the greedy Queen of Oogaboo and the wicked King of the Nomes, which threatens all of Oz.