Luca Paguro is a pre-teen sea monster living on the coast of the Italian city of Portorosso and spends his days herding a school of fish. His parents, mother Daniela and father Lorenzo, restrict him from going to the surface in fear that a human might kill him, but this restriction ends up making Luca feel bored. One day, when being conflicted about going to the surface or not, he meets another young sea monster named Alberto Scorfano, who has been on land many times on a small island near Portorosso and when he begs Luca to follow him, Luca discovers that he and Alberto can transform into humans when they get dry on land. They go to Alberto's hideout in a small tower on the island full of human collectables and Alberto claims that he lives with father. Luca finds a poster in the hideout showing a Vespa, an Italian scooter, and they soon decide to spend the next few days making one out of scratch all while Luca tries to keep his now double-life a secret from his parents with only his grandmother being clued in and keeping it a secret.
