A machinist on a Navy ship has two sons, both bolcheviks. When the revolution comes the Tsarist police captures the machinist to put pressure on his sons.
Zakhar Psaltyrev went through many ordeals in the royal fleet, where massacres and bullying of people became a custom. Only thanks to his natural intelligence and perseverance, the illiterate peasant boy managed to avoid the fate of many of his comrades, who became drunkards and lost their human dignity. Captain 1st Rank Lezvin, commander of the cruiser "Svyatoslav", himself suffocating in the difficult atmosphere of the tsarist autocracy, fatherly fell in love with his messenger for his simple Russian soul, quick-witted mind, love for the homeland and hatred of oppression. Zakhar learned a lot from Lezvin, but soon they had to part. Zakhar becomes an active underground Bolshevik.
Sea elements are fraught with many secrets. No crew is safe from emergencies that may occur at sea when they enter the open sea. The film tells a story that happened with the crew of an old tugboat "Dolphin". The ship fell into a terrible storm and, unable to overcome weather conditions, stood on stones. The crew led by the captain promptly leaves the ship, only the engineer Samokhin remains on the ship.
