Ozma of Oz( #3 in the Oz Series) by Lyman Frank Baum

It is the first Oz book where the majority of the action takes place outside of the Land of Oz. Only the final two chapters take place in Oz itself.[2] This reflects a subtle change in theme: in the first book, Oz is the dangerous land through which Dorothy must win her way back to Kansas; in the third, Oz is the end and aim of the book.[3] Dorothy's desire to return home is not as desperate as in the first book, and it is her uncle's need for her rather than hers for him that makes her return.