Five years ago, Faeryn Moss lost her family and home to a plague that swept her village. As the sole survivor, she was rumored to be a witch-a rumor she never denied because it was the truth. Ostracized and cast out in fear, she now lives a quiet life in a cave on the beach, alone with her magic and the only thing that never let her down, the only thing she loves: the sea. But when she sings up a storm borne from her grief in order to collect a net full of the sea's treasure, she gets more than she bargained for. There's a mermaid tangled within it.

Zale, washed into the net by the storm, is full of questions about humanity. Banished from her society for rescuing a drowning human, all she wants is a chance on land to start over. Seeing an opportunity for both of them to get what they want, Faeryn creates a transmutation rune-but as they go from reluctant allies to something else and Zale thaws Faeryn's frosty heart, they struggle with what's more important…their chance at a new beginning or their budding romance.

Everything changes when the kingdom's witch-hunting prince decides to take Zale as a member of the royal court and the potential future queen against her will. Faeryn must follow her across the sea so their transmutation rune can be completed by the next full moon or risk losing her love and her life to the very magic she cherishes.