The Cloud Searchers: A Graphic Novel (Amulet, 3) [Kibuishi, Kazu & Kibuishi, Kazu]

Emily, Navin, and their crew of resistance fighters charter an airship and set off in search of Cielis, a mythical city believed to be located on an island high above the clouds. The mysterious Leon Redbeard is their guide, and there's a surprising new addition to the crew: the Elf King's son, Trellis.