During the Winter War three Soviet soldiers perform a risky recon mission.

The story of three young Russsian adventurers against the background of post-revolutionary skirmishes in the Ukraine. The boys get mixed up with a wounded commissar and a marauding White Russian officer. They find themselves in all sorts of predicaments before the Reds arrive to save the day, and become the mascots of a troop of Bolshevik cavalry.

Andrei Latonin had jumped with a parachute many times before, but on the day of the holiday he got scared and stayed in the cockpit of the plane. Deeply upset by his failure, Latonin decides to leave his homeland forever and joins a steamship as a sailor. On the way, Andrei meets an expedition group heading for the crater of an active volcano and joins the scientists.