Despite their opposing personalities, a talented but directionless P.I. who is the black sheep of his family begrudgingly agrees to work as the in-house investigator for his overbearing mother, a successful attorney reeling from the recent dissolution of her marriage.

When troubled musical prodigy Charlotte seeks out Elizabeth, the new star pupil of her former school, the encounter sends both musicians down a sinister path with shocking consequences.

The coastal town of Bristol Cove is known for its legend of once being home to mermaids. When the arrival of a mysterious girl proves this folklore all too true, the battle between man and sea takes a very vicious turn as these predatory beings return to reclaim their right to the ocean.