Several years following the events of the original film, Ariel and Prince Eric are living blissfully as a married couple with their daughter, Melody. To shield Melody from the Sea Witch, Morgana, they have kept her mermaid lineage a secret. Driven by curiosity, Melody explores the ocean and encounters new companions. However, she may unwittingly become a tool in Morgana’s scheme to usurp King Triton’s dominion over the sea.