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.

Dik Trom hears that Oude Kee no longer has any money to buy food. Dik and his friends decide to help her and collect money for a small organ with which she can earn a living. They also give her some money, but it is stolen by Oude Kee's cousin. Dik wouldn't be Dik if he didn't catch the rascal after many exciting chases.

Dik Trom and his friends are on vacation and having a great time. They come up with all sorts of things to do to pass the time. They go fishing, make wooden carts, shoot bows and arrows, and get up to all sorts of mischief. Even Constable Flipse is not safe from their pranks. They are having so much fun that no one, not even a bully, can spoil it. They hope that they will experience something exciting during this vacation. Suddenly, they find a haunted house. Will that be scary enough?

Cor and Jan are two Dutch students who work in a hospital. A smallpox epidemic has broken out, but the country's capital is occupied by the army. Nevertheless, someone has to go outside the city to get a serum. Cor and Jan steal an old car and make their way through the military lines. It's not easy, but they're smart guys.