The hero of the film, the young Cossack Dmitry Peshkov, sets off in 1889 on a long journey from Blagoveshchensk in the Russian Far East to St. Petersburg to meet the Tsar and demand justice for the small Evenk people, humiliated and deprived of their horses by the Tsar's Russian officials. Serko, his little horse of the Manchurian breed, becomes his friend and companion in all adventures. During their long journey across the immense country, from the Amur River to the capital, Dmitry and Serko meet several peoples of Siberia - Evenks, Buryats, Manchurians, Tungus. The hero gets acquainted with the rites and customs of several small peoples, far from Western civilization, who believe in the forces of nature and worship their Gods. During these adventures, not only the wilderness represents a danger for the young man and his horse, but also and above all the men, in particular the governor of his region who tries by all means to prevent Dimitri from arriving in Saint Petersburg.
The meeting with the Parisian illusionist, Emile Fragonard, is a stroke of luck for the young Russian. Fragonard saves Dimitri from illness and prison. Fragonard's show, which the Frenchman dedicates to the young man, helps Dimitri to acquire notoriety and the aura of a hero allowing him one day to meet the Tsar's family. Having traveled more than 9000 kilometers, the young rider thus achieves the most fantastic feat.