Watch Secret Weapon for Free: How to Stream the Movie Online at 123Movies. . Based on a true story, 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 formed of ex-athletes is sent to rescue the secret weapon that the Germans can never find — no matter what it takes…