The film is based on the biography of Valeri Chkalov (1904 - 1938), a Russian pilot, who set several long distance flight records. Chkalov and his co-pilots Baidukov and Belyakov together had accomplished several non-stop long-distance flights. In June of 1937 Chkalov set the world record, covering 12000 kilometers in 63 hours of non-stop flight from Moscow to Vancouver, Washington, flying over the North Pole.
After the partisans Julia, Pavel and Sergei went out on a combat mission, the detachment was surrounded and destroyed by punishers. Years later, a document was discovered stating that one of the three was a traitor.
