Winter 1943, the most difficult period of the blockade of Leningrad. Of all the inhabitants of the village of Valeianovka only a mother and three children remain: the eldest - Sanka, the youngest - Egorka and the youngest a very small girl - Masha. The sick mother is already too weak to go into the forest in search of food. One day the older brother Sanka takes with him his younger brother, Egorka and they cross a minefield in order to find at least some food for the family. The brothers make an incredible find – after the recent battlefield bombardment, they find a huge wounded sheepdog. Sanka is faced with a dilemma, save the dog or the family from starvation. The children take him with them, but because of the terrible blizzard, they do not have time to return home and stay to sleep in Saraj. "It's not a dog. It's food", thinks Egorka. At night, the dog regains consciousness and saves the children from freezing, warming them with his body… On the neck of the shepherd dog, Egorka discovers a medal of a battalion of detector dogs of mines and realizes that the dog is a soldier. The child is confronted with an adult choice: – to save the dog or his family. But the dog is a soldier then….