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