To escape the rule of a mighty merman king determined to imprison her in the ocean, Ava Adair seeks refuge on the Lost Cove, an island haven for humans who discover the mermaid secret. With her merman mate, Carter Stevens, she strives to find a balance between her love of the land and her affinity to the ocean. After discovering she has the power to control the sea, she must learn why the ocean bestowed on her gifts meant for royalty. As her power grows and tension rises on the island, Ava struggles to remain on the shore though the ocean beckons her to return to the waves. Her unpredictable abilities make the ocean around the island dangerous for the human inhabitants, and Ava and Carter have no choice but to return to the water she fears. With the threat of discovery looming, Ava must harness her power to face the king and stop him before he destroys the land she loves and steals the life and ability the ocean has given her.