Scholastic The Cloud Searchers

Kazu Kibuishi's enchanting series about two ordinary children on a life-or-death mission continues 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. They must get help from the Guardian Council's Stonekeepers. The mysterious Leon Redbeard is their guide, and there's a surprising new addition to the crew: the Elf King's son, Trellis.