It was supposed to be a holiday to clear his mind and revive his career.

A chance look through the glass wall of Greaves Estate's underwater ballroom has Lucien Quinn racing against the clock to save a woman from drowning in the sea. But it's she who rescues him after he capsizes his boat in his mad rush, and she isn't only a woman. Calla is a mermaid, exiled from her people and recently escaped from a scientist's laboratory of horrors.

Struggling to overcome his own demons, Lucien welcomes Calla's friendship and offers her a place to hide. Except not all demons are grief or loneliness. Some are human, and they have Lucien and Calla squarely in their sights.