The three girls are bored, and the weather adds more fuel to their boredom. It is cold and icy outside, but the girls cannot sit in one place for too long, so they decide to pay the castle another visit. This time it is a solitary island and the three girls seem to be the only people there. They start roaming the island, but a sudden rainfall makes them seek shelter in the nearby house. There they meet a sad young girl, who is constantly looking at the sea. And soon the adventures start. "The Mermaid's Song" is the first story that takes place near water, but there is sufficient action and memories to fill at least two seas.