It is spring and final exams are approaching. Knud and the other boys are preparing to start highschool.

Uffe recruits three important new members from his model airplane building club. Alf Houlberg, his brother Kaj, and Knud Hornbo are factory workers in their early 20s. Alf tells Uffe that they have stolen six mortar grenades from the railway station near the factory, but they do not know how they work. He offers them to the Churchill Club.“The Professor” and Jens tinker with the grenades, trying to learn how to operate them. Finally, after a series of “near-suicidal experiments with explosives” (85), they figure out how to make the grenades ignite by lighting a small disc inside made of highly flammable magnesium.

The boys set aside two grenades for their “ultimate mission” (85), destroying the German vehicles in Budolfi square outside the monastery. First, they decide to do a “field test” (85) by blowing up boxcars containing German equipment at the rail yard. At the railway yard they unexpectedly come upon a couple kissing. The boys mock them until they leave. Alf and Uffe position themselves with pistols trained on German guards while Knud looks for a boxcar to ignite.