"Ozma of Oz" is the third book in the Oz series written by L. Frank Baum. It follows the adventures of Dorothy Gale, who is swept away to the magical land of Oz while on a journey to rescue her friend Billina, a talking hen. Together, they encounter various characters, including the Scarecrow and the Tin Woodman, as they face the evil Gnome King. In this story, Dorothy discovers that Ozma, the rightful ruler of Oz, has been kidnapped by the Gnome King. With the help of her friends, Dorothy embarks on a quest to save Ozma and restore peace to the land. The book explores themes of friendship, bravery, and the importance of home.