Pop star Harper disappeared from the celebrity spotlight for twelve months to conceal her mythical mermaid biology and protect her human lover Rhett from oceanic curses. When she finally returns to the entertainment industry, she is devastated to find Rhett preparing to marry her bitter professional rival out of spite.
To remain close and safeguard Rhett from dark secrets, Harper enters a fake relationship with Rhett's gentle brother Leo, driving Rhett into jealous frenzy. But when the magical cost of walking on two legs forces Harper's body to dissolve into ocean spray, Rhett discovers her silent sacrifice and begs the sea for redemption.
