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.

Two groups of children are playing war at the old fort. One group is from the local asylum center. They are all immersed in the game, as if they were in a real war. The goal is to capture the other group's flag at any cost! Missions are planned and the perfect strategy is devised. The girl Yasmin in particular shows great skill in warfare. The friendship between the children is strong, even though they are different, but one day the reality of war knocks on their door.