In the third installment of the thrilling Amulet series, Emily, Navin, and the gang 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. But is he ally or enemy? And will Emily ever be able to trust the voice of the Amulet?