The Witch on the Rainbow : Adventures in the Night Kingdom

Leonardo believed in ghosts, but he didn't actually expect to meet one until one night one showed up in his bedroom. The ghost wanted Leonardo's help in rescuing a girl held captive by the night witches. Leonardo didn't want to go by himself. His best friend wouldn't go with him. Thought he was coo-coo (crazy). But, Joanne, a new classmate, overheard them talking and offered to come with Leonardo. And so begins their adventure together to try to rescue the girl imprisoned by the witches in the Night Kingdom.