This was a war propaganda novel and does its work well. A nation, not named, at war with England and the USSR occupies a village in Northern Europe with a coal mine. The country is not named either. Obviously the occupying power is Germany and probably the country occupied is Norway.
The occupying power attempts to get production of the mine working, but eventually it all comes to naught. The populace reists and production stops.
What is interesting is how the novel proceeds from both sides. The occupying power men are mostly drafted mining employees and have good hearts. If you have seen the movie, Red Dawn, you will recognize much from this novel.