White Sun of the Desert

The setting is the east shore of the Caspian Sea (modern Turkmenistan) where the Red Army soldier Fyodor Sukhov has been fighting the Civil War in Russian Asia for a number of years. The movie opens with a panoramic shot of a bucolic Russian countryside. Katerina Matveyevna, Sukhov's beloved wife, is standing in a field. Awakening from this daydream, Sukhov is walking through the Central Asian desert â a stark contrast to his homeland.[2] He finds Sayid buried in the sand. Sayid, an austere Central Asian, will come to Sukhov's rescue in sticky situations throughout the movie. Sukhov frees Sayid, and they strike a friendly but reticent relationship. While traveling together they are caught up in a desert fight between a Red Army cavalry unit and Basmachi guerrillas. The cavalry unit commander, Rakhimov, leaves to Sukhov the harem, which was abandoned by the Basmachi leader Abdullah, for temporary protection. He also leaves a young Red Army soldier, Petrukha, to assist Sukhov with the task, and proceeds to pursue the fleeing Abdullah.
Sukhov and women from Abdullah's harem return to a nearby shore village. There, Sukhov charges the local museum's curator with protecting the women, and prepares to head home. Sukhov hopes to "modernize" the wives of the harem, and make them part of the modern society. He urges them to take off their burqa and reject polygamy. The wives are loath to do this, though, and as Sukhov takes on the role of protector, the wives declare him their new husband.
Soon, looking for a seaway across the border, Abdullah and his gang come to the same village and find Abdullah's wives. Sukhov is bound to stay. Hoping to obtain help and weapons, Sukhov and Petrukha visit Pavel Vereschagin, a former Tsar's customs official. Vereschagin warms to Petrukha who reminds him of his dead son, but after discussing the matter with his nagging wife, Vereschagin refuses. Sukhov finds a machine gun and a case of dynamite that he plants on Abdullah's ship. Meanwhile, Abdullah has confronted his wives, and is preparing to punish them for their "dishonor", as they did not kill themselves when Abdullah left them. Sukhov manages to capture and lock Abdullah as a hostage, but after he leaves, Abdullah convinces Gyulchatai, the youngest wife of the harem, to free him and then kills Gyulchatai and Petrukha.
The museum curator shows Sukhov an ancient underground passage that leads to the sea. Sukhov and the women of the harem attempt to escape through the passage, but on arriving at the seashore they are impelled to hide in a large empty oil tank. Abdullah discovers that and plans on setting the oil tank on fire.
Enraged at the cold-hearted murder of Petrukha, Vereschagin decides to help Sukhov and takes Abdullah's ship. Sayid also helps Sukhov, and together they fend off Abdullah's gang. Vereschagin, unaware of the dynamite on the ship and not hearing Sukhov's shouted warnings, tragically dies on the exploding ship.
Sukhov kills Abdullah and his gang, and returns the harem to Rakhimov. He then begins his journey home on foot, having refused a horse since a horse is merely "a nuisance".[3] Whether Sukhov will make it home to his beloved wife is unclear: the revolution is not over in Central Asia, and an exemplary Red Army soldier like Sukhov may well be needed.

Question: Which dead relative is Vereschagin reminded of by Petrukha?
Answer: son