In 1910, Baum hoped to end the Oz series and follow with a new series about a little girl named Trot and her sailor companion, Cap’n Bill. The Sea Fairies (1911) was the first book in the projected series and took Trot and Cap’n Bill under the sea where they had adventures with mermaids and other fantastic creatures. It was followed by Sky Island (1912) and then Baum returned to the Oz titles. He brought Trot and Cap’n Bill to Oz in the Scarecrow of Oz (1915).