Mermaids, with their sweet voices and beautiful looks, must seduce humans to feed on their hearts. But Dee refused to eat the heart of Lewen, the Prince of Erenbur, after falling in love with him. In return, she lost her voice, but gained two legs and a chance to meet her prince again on land. Meanwhile, Lewen's elder brother, Lewinel, returns home with Princess Irena of Ladivita, whom he has to marry for the sake of his nation. But when these four come together, everything will be thrown into chaos...