In her underwater utopia of Rayanori, Cordelia has always felt like an outsider. Apart from her best friend Brooke and Brooke's older brother Adrian, Cordelia's senior year has been a complete letdown. Coupled with her hostile home life, Cordelia feels lost. Until one day, Adrian and Cordelia happen to spot someone sinking in the sea through the dome's large windows. Adrian acts fast and plucks a strange foreigner named Kai from the water moments from death. To their shock, she claims to be from the drylands they call Cephas, far above their dome. Knowing the danger of even mentioning the old world, Adrian and Cordelia hide Kai away in a secret bunker. Befriending the kind young woman, the pair secretly plot to find a way to send Kai home, though Cordelia doubts her claims. Then Adrian gifts her with an ancient device known as a cellphone, and Cordelia is fascinated. As time goes on, Cordelia finds herself drawn to the foreigner, eager to learn of the drylands thought to have been destroyed over 500 years ago by humankind's destructive ways. Rayanorians know of their past, and the dying world their ancient pioneers left long ago to forge a new, better life beneath the waves, but the history they have been taught is not as it seems. When Brooke discovers Kai and the plan to send her home, she wants in. But not before someone has alerted the authorities to their activities, thus discovering Cordelia's ancient cellphone relic. Facing imprisonment or worse, Cordelia must find a way to save Kai and then...herself.