Once there was a boy called Luka, who lived in a town beside a deep silvery sea. Luka longed to splash in the surf and dive beneath silver-bright waves, but he couldn't swim. One day, Luka sees a girl gliding through the waves, dipping and soaring like a fish.

Luka has never seen anyone swim so well. Sylvia teaches Luka how to swim, and that night, Luka dreams that Sylvia is a mermaid and they have a beautiful underwater adventure visiting the mermaid palace. And when Luka starts school, Sylvia is there!

The other children crowd around her to ask why she's in a wheelchair, and Luka tells everyone that it's because Sylvia is a mermaid. Luka knows that to him she will always be a mermaid and they will have a thousand more adventures together.