A young girl Lida in the midst of the Great Patriotic War lives in a small town in the rear. When all the men went to the front, Lida had only one true friend a dog named Kashtan, a rootless, but very loyal dog. But the cruel war reached Lida’s friend too other. Kashtan was seen on the street and "mobilized" in the ranks of the Soviet Army and as a dog demolition. Wanting to save Kashtan from such a fate, Lida appealed for help to one of the soldiers of Special Section. The fighter named Starikov promises to help save the dog, but soon realizes that not only the given word links him with Lida: the girl and the young man have deep sympathy for each other. But the fragile happiness of two lovers will not last long – very early they will receive an order about the dissolution and destruction of trained dogs, as they are no longer needed.