Der Uranberg (2010)

Kurt Meinel returns from his Soviet POW camp to his native mining village, hating Hitler enough for wrecking Europe to support the Russian regional occupation commander Bursky, in charge of mining uranium for a project to match the US atomic bomb. Kurt is admitted to mining geology training and assigned to the mine. His father, who hates the Russian invaders, warns him about a tradition against a 'lake' hidden within the mountain. Kurt starts an affair with the general's daughter, which exposes them to terrible punishments.