Young Luca and his best friend, Alberto, summon up the courage to visit the picturesque fishing village of Portorosso. However, the boys share and hide a great secret: they are not ordinary children but harmless sea monsters who live underwater, eager to find out what lies above the sea's surface. Before long, adventure after adventure and experience after experience, the two wide-eyed explorers will discover the true meaning of freedom, the importance of family, and the catalytic power of acceptance.