One thousand years after a cataclysmic event leaves humanity on the brink of extinction, the descendants of the chosen survivors take refuge in thirteen contingency shelters buried deep underground, at the bottom of the ocean, and in the far reaches of outer space. In the underwater 13th Continuum, sixteen-year-old Myra Jackson has heard rumors and whisperings all her life of a magical place called ""The Surface" where people could breathe fresh air, feel the warmth of something called sunlight on their skin, and see things known as stars and trees and mountains. Myra has never dared to ask whether the stories are true—since the very act of speaking such words aloud is an offense punishable by death. But after she discovers that the air supply aboard her underwater colony is running out, she realizes that her only hope for survival is to find this mysterious place. To get there, she must first recover the only guide to the Surface―the Beacon, an ancient device that also connects her to Captain Aero Wright, a dashing young soldier from one of the only remaining space colonies. With the fate of all humankind depending on them, Myra and Aero must escape the tyrannical forces that rule their colonies, journey through the black depths of the ocean and across the cold void of space, and find each other on the Surface that their ancestors once called home.