On an ocean voyage with her uncle Henry to Australia, Dorothy is blown into the sea by a storm.
She takes refuge on a floating chicken-coop, which washes ashore, along with the coop and a hen in it.
 The hen is able to speak; Dorothy gives it the name "Billina".
 Exploring the land, Dorothy and Billina are menaced by a tribe of brightly dressed "Wheelers", who have wheels instead of hands and feet.
 They also find a clockwork man named Tik-Tok (one of the first intelligent humanoid automatons in literature), who joins them.

Tik-Tok informs Dorothy and Billina that they are in the Land of Ev, which currently has no competent ruler, its king having committed suicide after selling his family to the Nome King.
The three visit the castle of Princess Langwidere, who has many exchangeable, detachable heads.
When Dorothy refuses to let Langwidere take her head and add it to her collection, Langwidere has a tantrum and locks Dorothy in a high tower within the palace.

Luckily, Princess Ozma and her Royal Court of Oz (many of whom appeared in the two previous Oz books) just happen to cross over the Deadly Desert on a mission to free the royal family from the Nome King.
Upon arriving, Ozma takes charge and has Dorothy, Billina and Tik-Tok released from Langwidere's custody.
The three join Ozma's expedition to the Kingdom of the Nomes.

When they arrive, the Nome King reveals that he has magically transformed the royal family into decor ornaments.
When Ozma asks him to release them, he offers a bargain: the Oz people may enter his chambers and try to guess which of the Nome King's many ornaments they are, but if they fail to guess correctly, they will also become ornaments themselves.
Ozma, the twenty-seven soldiers of the Royal Army of Oz, including the Scarecrow, the Tin Woodman, and Tik-Tok, all suffer this bizarre fate.
Dorothy luckily selects one ornament which turns out to be one of the royal family's young princes.
 
That night, Billina overhears the Nome King discussing his transformations with another Nome, and learns how to recognize, by color, which ornaments are transformed, people.
She also learns that the King's magic powers come from the Magic Belt that he wears.
 She is, therefore, able to free all the transformations.
By exploiting the Nomes' fear of eggs, the Oz people are able to capture the magic belt and escape the Nome Kingdom with the royal family of Ev.

After returning the royal family of Ev to their throne, Ozma, Dorothy, and the others finally return to the country of Oz where a great victory celebration is held in the Emerald City's royal palace.
Dorothy is officially made a Princess of Oz, Billina elects to remain in Oz, and Ozma uses the magic belt to send Dorothy to Kansas where she is happily reunited with her Uncle Henry.
On an ocean voyage with her uncle Henry to Australia, Dorothy is blown into the sea by a storm. She takes refuge on a floating chicken-coop, which washes ashore, along with the coop and a hen in it.  The hen is able to speak; Dorothy gives it the name "Billina".  Exploring the land, Dorothy and Billina are menaced by a tribe of brightly dressed "Wheelers", who have wheels instead of hands and feet.  They also find a clockwork man named Tik-Tok (one of the first intelligent humanoid automatons in literature), who joins them.
Tik-Tok informs Dorothy and Billina that they are in the Land of Ev, which currently has no competent ruler, its king having committed suicide after selling his family to the Nome King. The three visit the castle of Princess Langwidere, who has many exchangeable, detachable heads. When Dorothy refuses to let Langwidere take her head and add it to her collection, Langwidere has a tantrum and locks Dorothy in a high tower within the palace.
Luckily, Princess Ozma and her Royal Court of Oz (many of whom appeared in the two previous Oz books) just happen to cross over the Deadly Desert on a mission to free the royal family from the Nome King. Upon arriving, Ozma takes charge and has Dorothy, Billina and Tik-Tok released from Langwidere's custody. The three join Ozma's expedition to the Kingdom of the Nomes.
When they arrive, the Nome King reveals that he has magically transformed the royal family into decor ornaments. When Ozma asks him to release them, he offers a bargain: the Oz people may enter his chambers and try to guess which of the Nome King's many ornaments they are, but if they fail to guess correctly, they will also become ornaments themselves. Ozma, the twenty-seven soldiers of the Royal Army of Oz, including the Scarecrow, the Tin Woodman, and Tik-Tok, all suffer this bizarre fate. Dorothy luckily selects one ornament which turns out to be one of the royal family's young princes.  
That night, Billina overhears the Nome King discussing his transformations with another Nome, and learns how to recognize, by color, which ornaments are transformed, people. She also learns that the King's magic powers come from the Magic Belt that he wears.  She is, therefore, able to free all the transformations. By exploiting the Nomes' fear of eggs, the Oz people are able to capture the magic belt and escape the Nome Kingdom with the royal family of Ev.
After returning the royal family of Ev to their throne, Ozma, Dorothy, and the others finally return to the country of Oz where a great victory celebration is held in the Emerald City's royal palace. Dorothy is officially made a Princess of Oz, Billina elects to remain in Oz, and Ozma uses the magic belt to send Dorothy to Kansas where she is happily reunited with her Uncle Henry.
Ozma of Oz