The last summer before the end of World War II, Walter Proska is posted to a small unit tasked with ensuring the safety of a railway line deep in the forest on the border with Ukraine and Byelorussia. In this swampy region, a handful of men-stunned by the heat, attacked by mosquitoes, and abandoned by their own troops in the face of the resistance-must also submit to the increasingly absurd and inhuman orders of their superior. Time passes, and the soldiers isolate themselves, haunted by madness and the desire for death. An encounter with a young Polish partisan, Wanda, makes Proska further doubt the validity of his oath of allegiance, and he seeks to answer the questions that obsess him.