A disaster happened: Caruso, Hanna's favorite cat, disappeared! However, a magical pencil came to help and took the girl and her friend Henry to the very bottom of the ocean. In a strange way, they were able to swim like fish, as well as communicate with underwater inhabitants. The children found out that the shark police arrested a hairy fish. It must be dear Caruso! Read more and find out if Hanna and Henry managed to save their friend!