It's the Great Patriotic War. The Red Army has had to retreat in a hurry and left their top secret weapon, "Katyusha", behind. A group of eight soldiers is sent to do everything possible to not let Katyusha fall into German hands.

The film tells about the famous Soviet rocket launcher nicknamed "Katyusha", which was kept in great secrecy during World War 2. One of these unique killing machines has drowned during an unexpected retreat of the Russian troops. A special unit is sent to rescue the secret weapon that the Germans can never find - no matter what it takes .