Calder White lives in the cold, clear waters of Lake Superior, the only brother in a family of murderous mermaids. To survive, Calder and his sisters prey on humans and absorb their positive energy. Usually, they select their victims at random, but this time around, the clan chooses to take revenge on Jason Hancock, the man they blame for their mother's death.

Calder's job is to gain Hancock's trust by getting close to his family. Relying on his irresistible good looks and charm, Calder sets out to seduce Hancock's daughter Lily. Easy enough, but Calder ruins the plan by falling in love--just as Lily starts to suspect there's more to the monster-in-the-lake legends than she ever imagined, and just as the mermaids threaten to take matters into their own hands, forcing Calder to choose between them and the girl he loves.

One thing's for sure: whatever Calder decides, the outcome won't be pretty.