Billie Turf and Dolfie have to stay at boarding school during the summer holidays because their report cards are too poor. Everything goes smoothly until Kwel comes up with an invention that turns water into gasoline with a pill.

Cheeky youngster Dik Trom must outsmart the menacing local gang known as the Red Hand and the officious constable Flipsen. When a gang kidnaps a disabled friend and holds him in an abandoned house, Dik—never one to back down—leads a daring rescue mission with some unexpected help.