Yesterday's Leningrad schoolgirl Masha Yablochkina, after a fierce
blockade winter of 1941-1942, comes to the railway courses hoping to
survive and gain strength. From there, the girl 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. So the
heroine gets into the 48th locomotive column of the special reserve
NKPS, which at the cost of the deadly risk is to deliver to Leningrad
75% of all cargo and military equipment.