The Steel Hearts: In occupied Silesia, resistance is organizing. In close contact with the miners and led by an engineer, a group of partisans prepare the sabotage of the steel combine. The going will be tough as the place is closely guarded by the Nazis. But despite a denunciation from a traitor and several violent deaths, they get going and the operation is a success. But the Red Army is approaching and now the coal production must not be sabotaged anymore. On the contrary, the partisans must prevent the Germans from destroying the steel mill and the coal mine...