Emily enjoys being half-mermaid, but her Mother has a difficult time processing that Emily won't be having academic studies any longer. Emily's parents start to argue a lot, and she becomes worried that they will break up. Emily then finds a ring that was King Neptune's wedding ring, which had become a cursed ring. Out of anger, King Neptune decides to ban humans and mermaids becoming married ever again. Emily is forced to either become fully human or fully mermaid. Emily must locate the other ring to break the curse and to keep being half-mer, but will she be able to before it's too late?