There is the 25th day of World War II. The Soviet army is fighting fiercely in a cauldron near Kanev, trying to keep the enemy out of Kiev. Knowing that the Russian units are running out of ammunition, the Nazi command begins the operation "Panther" in lightning capture and defeat of the defenders of Kiev. The only hope of those who were surrounded by the troops was the N56 armored train. Its task is to stop the advance of the Nazis and break through the siege ring, creating a saving corridor for Russian soldiers.