Andrei Vysotina, who has just graduated from the Naval Academy, is appointed commander of the ship Derzhavny. The hero challenges the commander of another ship in the Black Sea Fleet, whose wife he was once in love with.

A black child rescued from by Russian sailors, whom they name Maksimka, having overcome his fear of white people, turns out to be an unusually smart and kind little boy. The rude drunken sailor Ivan Luchkin was especially attached to the boy. Once it was Maksimka who managed to save Luchkin from foreign recruiters of labor. For resourcefulness and courage, the young hero is enlisted in the team of the corvette and becomes the cabin boy of the Russian fleet.