E. is content with a solitary life in her extraordinary underwater home, until the discovery of a strange, beautiful creature outside her window prompts her to begin a correspondence with renowned scholar Henerey Clel. The letters they share are filled with passion, at first for their mutual interests, and then, inevitably, for each other. But when a mysterious seaquake destroys E.'s home, she and Henerey vanish. A year later, E.'s sister Sophy and Henerey's brother, Vyerin, must piece together the letters, sketches and field notes left behind and learn what their siblings’ disappearances might mean for life as they know it.