During the defense of Leningrad in the winter of 1941-1942, several women are tasked with delivering cargo and military equipment via the railways, facing German interference at every turn.

After a fierce blockade in the winter of 1941-1942, Masha Yablochkina, a Leningrad schoolgirl, comes to the railway courses hoping to survive and gain strength. From there, she is sent to the construction of the Shlisselburg Highway, which connects the city with the Great Land and is in direct sight of German artillery. The heroine gets into the 48th locomotive column of the special reserve NKPS, where she risks her life to deliver to Leningrad 75% of all cargo and military equipment.