Overview
Bill Bergson and the White Rose Rescue (original Swedish title Kalle Blomkvist och Rasmus) is the third and last novel about the Swedish "master detective" Kalle Blomkvist, written by Astrid Lindgren.
It was published in 1953, during the Cold War. The professor's invention of impervious light metal is significant to the war industry and the kidnappers' motive is not financial, it's political. Nicke, a kidnapper, says that he "could do what else for the thing and everything was right which could promote the thing" ("kunde göra vad som helst för saken och allt var rätt som kunde främja saken"), but the engineer Peters threatened him: "Jag behöver väl inte påminna dej om hur det går för såna som försöker hoppa av?" ("I don't need to tell you how it goes for people who tries to defect?").
Plot
The last summer Gren was murdered. Now it's summer again and in Lillköping the "war" between "Vita Rosen" (Kalle, Anders and Eva-Lotta) and "Röda Rosen" (Sixten, Benka and Jonte) continues.
Down the castle ruins outside of Lillköping, Eklund's house is located. One day when Kalle, Eva-Lotta and Anders pass, they meet a 5-year-old boy called Rasmus who lives there with his father professor Rasmusson, who tells that he has invented an impervious light metal.
From Wikipedia (CC BY-SA 4.0).