Strannye vzroslye (1974)

Before the eyes of the theater gaffer Peter Ryabikov, a first-grader girl runs across the road in front of a nearby watering machine. Peter intercepts her and, wanting to punish, decides to take her home, to her parents. However, when he takes her there, it turns out that this is an orphanage, and the girl, whose friends call her Tonya (her real name is Juliet), is an orphan. Peter is no longer young, he lives in a communal apartment, he has a wife, but no children. Feeling also some blame for Tonya, he wants to adopt her. So in a large apartment, where before lived only adults, a little girl appears, which completely changes their monotonous life.