A Russian engineer Petr Garin possesses a unique beam-shooting weapon that can destroy any target. His goal is to achieve world domination with the help of this weapon. Vasily Shelga is out to stop him and also to prevent others getting possession of this weapon.
In the first days of the Second World War, a young woman with three children is evacuated from the front-line zone to the Urals. After some time, she receives a funeral for her husband. But she has her little sons with her. The eldest son Kolya becomes a reliable assistant to his mother.
After starting learning in a technical school a young student Sergey Berendeev proves to everybody that he's a real inventor.
