Mästerdetektiven Blomkvist(1947)

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.