The letter arrives: Ondine's final assignment in her teaching program that will finally - finally - secure her future on the Isle of Mardona. The process has been difficult due mainly to her father's Neridian bloodline, but also the legacy her mother left in the wake of her death. But this final step will put all of that in the past where it belongs, and Ondine will settle into her place on the Isle. But there's a problem. She has been assigned to teach at Regiatus: an underwater school in deep Neridia. Not only is Neridia dangerous - especially for Ondine - but her assignment to the depths throws her plans into chaos and pulls her into a rip tide of discoveries about herself, her Isle, and the spiritual power of the ocean herself. Ondine must decide between a secure and planned future on the Isle she knows, or risk that future - and possibly her life - to pursue a world she's only begun to understand.