The story concerns the events in Saint Petersburg on the eve of the First World War. Private detective Petya Chukhontsev, a law student who has not completed his studies, investigates the case of the murdered inventor Kuklin. He was murdered exactly as he predicted during a New Year's visit to Chukhontsev. While investigating the Kuklin case, Petya soon realizes that the central figure in this case is the German Scholz, the owner, who cheaply buys up the inventions of Russian craftsmen and hands them over to the spy Siegfried Gay, an advisor to the German embassy. . However, Petya will soon understand that it is better to mind his own business...