The Squadron leader throws big a party where one of his colleagues is going to demonstrate a new type of explosive substance.
Torsten and Sven are in love with Inger, who prefers Sven. Due to jealousy, Torsten destroys the radio system aboard the fishing boat as Sven will release the following morning. During the fishing season it blows up, but as the radio is not working, the crew does not know anything about the danger.
It's summer. Kalle, Eva-Lotta and Anders have formed a gang, the White Rose. They are in playful battle with Red Rose gang. A relative of Eva-Lotta's mother, Uncle Einar, come to visit and Kalle notice immediately that he is behaving strangely. Einar seems to have hidden something in a closed mine outside town. Two mysterious strangers appear.
