Julius moves to Kiel and meets Max at school, who unfortunately does not want to be friends with him. One day, Max disappears, and Julius gets the chance to prove what he can do - with unexpected help from an animal. From that moment on, they become thick friends! During a vacation in South Tyrol, the two meet Mila, and the adventure continues. While diving in a lake, they get trapped in an underwater cave. Will they manage to free themselves? Even after that, things remain turbulent: a car accident, a nasty crook, mysterious diary entries, plans for a surprise party, and a dramatic kidnapping ensure that the three cannot find peace. And then there’s also the dog Amy and the horse Filine - together, they make a fantastic team!.