F&F have used their bicycles to build a flying machine that Lupo steals on the run from a woodpecker. Prof. Knox has built a modern dowsing rod and wants to find a precious mineral - Limpy and Stinky got wind of it and are thinking of diamonds. The first buyer in the new shop is to be given a skateboard as a gift in the morning. F&F and Lupo are already camped in front of the shop at night...but Lupinchen is the laughing fourth. The family is sitting in the car and is on its way to an amusement park. To avoid a traffic jam, dad takes the road through fields and forests - but unexpected dangers like bulls and forest clearing are lurking there.