Lydia and the Mist Rider by Dj Mack
When her older brother Thaddeus is mysteriously kidnapped by the Spellbinder, 11-year-old Lydia sets off to find him in the Misty Sea. Picked up by the crew of a flying ship, the Dolphin, Lydia becomes the apprentice of Ambrosia, a Stargazer. Ambrosia is trying to find other children who have disappeared, including her own son. Determined to solve the mystery, Lydia must learn stargazing magic and ready herself to confront the Spellbinder.
