The Serpent Sea (Books of the Raksura #2)
Author: Martha Wells
Desc: Moon once a solitary wanderer has become consort to Jade sister queen of the Indigo Cloud court. Together they travel with their people on a pair of flying ships in hopes of finding a new home for their colony. Moon finally feels like he's found a tribe where he belongs. But when the travelers reach the ancestral home of Indigo Cloud shrouded within the trunk of a mountain-sized tree they discover a blight infecting its core. Nearby they find the remains of the invaders who may be responsible as well as evidence of a devastating theft. This discovery sends Moon and the hunters of Indigo Cloud on a quest for the heartstone of the tree — a quest that will lead them far away across the Serpent Sea.