Rasmus Baltzersen

Mads "Crumb" Krumborg need a new bike so he can take part in an important race against a neighboring school. But it will be difficult to afford to buy a new printer, since the boy's father suddenly decides to terminate his job to invent a machine that according to him will change the world. At the same time a couple of crooks wind of his father's invention, and when the family Krum Borg's future is in problems, Crumb and his siblings to the occasion and save the day.

What is happening in the class? Who are friends, who are enemies - and who has had a mishap? The pupils have yet another day ahead of them.