A long time ago, Rab learned the secret of the planet he calls home. Now, after years of enslavement under the Feathers, Rab considers an escape with Cloud, hoping to find refuge with the few surviving Top-Siders who still live free in the west. But there have been dire warnings of a new breed of predator in the skies and the Kun, leader of the Feathers, has deployed his human captives to fortify the settlement's defences.

When the child of Rab's adopted son disappears and the Kun's settlement comes under siege, an unlikely friend surfaces and events are set in motion that will shatter perceptions and radically shift the course of the future.