Katy Browning, 17, comes to a saddened Florida home at Christmas time. The disappearance of her baby brother, three years ago, had turned the happy, prosperous Brownings into a family beset with cares. Not the least of them, Katy finds, is the problem of local fishing rights on Cormorant Key and the animosities of the de Angelis and Carl Huber, who had once been friendly. As Katy gets to know young Randy Watrous, Carl's stepbrother, she learns the details of Carl's unfortunate marriage to one of the de Angeli sisters, who had been killed in an accident while Carl was at sea. Only their small son survived. But as Randy and Katy put two and two together, it turns out that a less well intentioned de Angeli sister had kidnapped the Browning baby to palm off as her own nephew to Carl. An easy lock for this Key.