Sea level has fallen six hundred feet. Many people are cocooned in sleep. Where the long winter is not grinding away at what remains of Earth's great cities, humans dwell behind fences. Keeping guard against attacks by specters emerging from the ocean, on the muddy edge of the exposed continental shelf, is Hudson MacDuff. His mother, Lucy, once a hero of the Great Eclipse, wants her son to build a life beyond the dystopian world he has inherited. Hudson feels bound to look after his brother, Owen, and his friend, Benny, and yet his gaze turns upward, Into a Hearkening Sky. Before he can ever touch the stars, though, Hudson must make an impossible journey into the depths to sever the cords to which he clings.

Into a Hearkening Sky brings to a climax the events of its two acclaimed prequels in the Hyperbolia Series-Under a Darkening Moon and Within a Wakening Earth-while forging into a family their characters, who learn how their lives and powers have been shaped to send a beacon of hope into the abyss.