After the terrible blockade winter in 1941-1942 , Masha Yablochkina, just graduated from Leningrad school, attends the railway courses, in order to work in this field later. She hopes to survive and to gain strength during study. But from there the girl is sent to the construction of the Shlisselburg railway, that is supposed to connect the city with the big land and which is in a direct line of sight of the German artillery. This is how the main character gets to the 48th Locomotive Column of the special reserve of People’s Commissariat of Railways of USSR, which delivered 75% of all cargo and military equipment to Leningrad at the cost of deadly risk.