A new design aircraft flies higher, farther and faster than all others. Enemy intelligence agents are trying to infiltrate the cottage of the inventor Professor Bogolyubov and steal the drawings of the aircraft.

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

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.