Howl's Moving Castle
Castle in the Air is a young adult fantasy novel written by Diana Wynne Jones and first published in 1990. The novel is a sequel to "Howl's Moving Castle" and is set in the same fantasy world, though it follows the adventures of Abdullah rather than Sophie Hatter. The plot is based on stories from the "Arabian Nights". The book features many of the characters from "Howl's Moving Castle" as supporting characters, often under some sort of disguise.