To help out his friend Lenya, Yura steals a Stradivarius violin belonging to the professor from his grandfather, a violin maker. Having learned about everything, the professor begins to study with the talented Lenya. Circus performers persuade Lenya to give up the violin and perform in the circus...

The action takes place in the late 1920s in Ukraine. The exposure of a counter-revolutionary agent who has infiltrated the Soviet scientific community. The film has survived without the 6th part.