As Amara, a former mero, adapts to life on land, she feels the strong call of the sea, summoning her voice, her song. A sound both beautiful and dangerous to human ears.
When she and her boyfriend, Tyler take a trip to Hawaii for spring break, the pull is stronger than ever and she finds herself singing on the shore.
Later, she meets Tian, a local, who invites her to a luau and encourages her to sing. After the couple has an argument, leaving her on the beach, the siren song comes to her lips and Tian to her side. At that, despite trying to resist, she sings the night away and sand succumbs to the lure of the ocean.
There, she loses one of her greatest treasures as her past collides with the present, and powerful forces intend to use her voice against those on land.