After betrayal drives marine researcher Maren Ward to a stormy pier, she rescues a wounded boy who is actually Darius, fallen Lord of the Seven Tides. A tide mark binds their lives and draws her into an underwater coup. As her mixed Eryndor blood awakens, Maren can read water`s memories and open gates between worlds. Together, they expose Cassian`s war plot, break the crown`s monopoly, and choose an equal love.