Later he finds that the dog ran out the apartment door, maybe to look for him, and is lost. There is a scene of documentary simplicity, in which Umberto seeks Flag at the dog pound, and learns how unwanted dogs are put to death. He peers helplessly into a cage so filled with barking, scrambling dogs that he cannot see for sure if Flag is even there. When he finds the dog, note how De Sica shows them greeting one another. This whole passage is all the more affecting because the movie doesn't milk it for tears, but simply shows it happening.