The Song of the Mermaid: The Story of the Movie! Hanne, Marthe and Julia are having the holiday of a lifetime in the southern coastal village of Porto Sirente... until a mysterious spell transforms them into beautiful mermaids! If the girls don't want to stand out, they will have to avoid water and that is of course easier said than done and there is danger lurking. In the coastal village where the three are enjoying their holiday, the residents see mermaids as monsters for some reason. When the girls discover that after three days they will remain mermaids forever, a race against time begins to break the spell. If they don't succeed in time, Hanne, Marthe and Julia will be mermaids forever, and never K3 again...