Because her parents are going on holiday with her aunt, Johanna lives with her cousin Robert and her grandfather. Together with two neighbourhood boys, the children secretly go on an adventurous voyage of discovery down the Weser in a rowing boat at night. Grandpa tries to hide the disappearance from the rest of the family and follows the children in his motorboat. Just as the returned holidaymakers meet up with the grandfather in an inn, the children turn up. Together with their grandfather, with whom they share a secret from now on, they cover the rest of the distance to the sea.
A real children's film classic! The KinderFilmWelt writes: "Pure adventurousness leads the young heroes of this story on a journey in which only they, and not the adults, decide where to go. Yet it never gets so exciting that the hairs on the back of the audience's neck stand on end.... Because exciting and funny scenes alternate again and again and the film is told very calmly and slowly - it is just a bit older. At that time, in the 80s, it was something very special because very few children's films were made. Especially not those that are so much fun and show children's characters who are cheeky, strong and brave. Get on board and experience an exciting and funny river adventure with Robert, Johanna and their pirate gang."