Jan Kruyk

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.

Sjors and Sjimmie have received a magic ring as a thank you for their help to a well-known archaeologist. They end up in the Middle Ages with their regular opponents, Boris and Pedro, because of the magic ring. The magic ring makes wishes come true, but Sjors and Sjimmie don't know that. They are accused of witchcraft and are in danger of being burned at the stake.

Colonel Brulgraag has found the will of King Krijn XXIV of Schiermeeuwen. Whoever finds Krijn's Sword will be the new king. The colonel asks Sjors and Sjimmie to search for the sword so that it can be taken to a museum and not used by Krispijn to gain power.

Billie Turf is a student at Dennenheuvel boarding school. According to his teacher Kwel, he is unreliable, a good-for-nothing, and a liar who can only think about good food. Due to his boorish behavior during various activities, such as training for sports days, washing a car, and going on a fishing trip with his teacher, Billie repeatedly comes into conflict with the boarding school's management, which results in him receiving the same punishment every time: cleaning duty and going to bed without dinner. He is only resourceful and clever when it comes to obtaining food. His good nature is finally revealed when, together with Jossie, the director's niece, he manages to find the kidnapped student Kareltje and the ransom money.