In a world overtaken by floodwaters, all that is left are mountaintop colonies and a vast ocean. As Myra and her daughter Pearl, navigate the new world by boat, she mourns the loss of Row, her other daughter years ago. But after a violent controntation with a stranger, Myra hears word that Row is alive and near. On her journey, she joins with a larger ship, befriends other seekers, and comes to the realization that maybe saving Row could put Pearl and her friends in danger.