"I wish I was away in Ingo Far across the briny sea, Sailing over deepest waters Where love nor care never trouble me. . . ." By the Cornwall coast where Sapphire lives with her family, it's easy to hear the call of the sea. Too easy. When the sea called to Sapphy's father, he vanished from her life. When the sea called to her brother, he started disappearing for hours on end. And now the sea is calling to Sapphy, and she feels its pull more strongly than she's ever felt anything in her life. In a novel full of longing, mystery, and magic, Helen Dunmore takes us to a new world that has the power both to captivate and to destroy. At the waterline, the two worlds of Air and Ingo meet. Sapphy and her brother, Conor, find themselves at the boundary between these worlds, in a place of danger and amazing discoveries.