Soviet propaganda film set in Moscow. Talented inventor Igor Krymov is the head of a top secret lab in the Red Army. He is befriended by Nora, a foreign spy working undercover as interpreter. Nora gives Igor a glass of champaign with poison, and while he is unconscious, she takes copies of his secret files. Igor is manipulated by a network of foreign spies, but all persons involved are watched by the KGB...