August 1941. The commissar, fearing for the life of the German anti‑fascist communist Rettel, sends him and his son Otto in an ambulance train to the rear. During a raid, Rettel is killed, and the eighteen‑year‑old boy ends up with the combat crew led by Senior Sergeant Zhigarev, who has received an urgent order to hold the position — or, in the worst‑case scenario, to blow up the bridge. Zhigarev clearly doesn’t trust the young German...