The musical "Nord-Ost" is based on "Two Captains", a novel by Veniamin Kaverin. The life of two generations is depicted in the background of real events of Russian history. A romantic epoch set in the context of the discovery of the north-east lands, the search for a Northern sea route through the ice of the Arctic ocean, stormy revolution years, World War II, the Siege of Leningrad, and the development of Russian polar aviation - these are the milestones through which the plot is moved. The spectator watches the growth and maturity of the musical's characters, Sanya Grigoriyev and his friends. .
1915. As a child, Sanya witnesses the murder of a postman and is left with the mail bag containing the last letter of a captain whose ship was taken prisoner by ice. Sanya's father is wrongfully accused of the postman's murder, but the boy is mute and can't explain the truth. His father dies in prison. Time goes by. The country falls into the throes of the Civil War. The boy struggles to learn to speak and overcomes his muteness. .
On his own, Sanya comes to Moscow and is placed in an orphanage, where he meets new friends-including Romashov. By chance, Sanya grows close to the family of Nikolai Antonovich Tatarinov, the director of the orphanage. The family presents a strange knot of relationships: Maria Vasilyevna, the widow of captain Tatarinov, and her daughter Katya have lived for many years in the home of Nikolai Antonovich, the brother of the deceased captain. .
The end of the '20s. Sanya is graduating. He is in love with Katya. Katya tells him about her father. Suddenly, Sanya realizes that Katya's father and the captain whose letter he accidentally possessed as a child are the same person. Sanya tells Katya and Maria Vasilyevna the contents of the letter. In his last communication, captain Tatarinov accuses his brother Nikolai of his death. Nikolai Antonvich and Romashov also find out about the letter.