Engineer Dukalsky arrives from Moscow on the instructions of an underground anti-Soviet center to the Baltic Shipyard in order to take possession of the blueprints of a powerful ship engine. The pest meets the author of the project - a young and incorruptible self-taught master Ivanov. After a series of unsuccessful attempts to buy out or steal the drawings from the author, Dukalsky decides to take Ivanov with him. Criminal Investigation Officers will attack the trail of criminals.

Pyotr, backward lad from poor village, comes to town desperate for work. He's hired as replacement ("scab") worker at big metallurgical factory, which is in the throes of a strike organized by the Bolsheviks (communists). Deceitful industrialist's son involves naive young man in an attempt to murder Bolshevik leader.