Based on the novel by Tamara Zinberg "Seventh Symphony". Siege of Leningrad, 1942. Despaired Nina Voronova can't stand starvation and cold any longer. She evacuates from the city, leaving her little son in a deadly cold apartment. He is found by Katya, an orphaned teenager girl from the next door, right before his house is destroyed by bombs. Katya claims he's her brother, and manages to get extra food provision from the district administration using boy's certificate of birth. In the meantime she helps to nurse injured soldiers in the local hospital. One of them - Alexey Voronov - realizes the little boy is his son.