Isla may be a mermaid princess, but she's never felt at home in her undersea kingdom. Instead she dreams of the day her people can return to the surface--and the boy whose life she once saved. But while Isla foresees danger for her people beneath the ocean, she has no concept of the dark forces working to keep her people submerged. When an impetuous vow sets her on the course of the truth, Isla discovers that shadowy foes beset the kingdoms...