A seventeen-year-old nurse lives in a small provincial town, who is raised by a strict surgeon grandmother. One night, Lerka runs away from home and goes to Moscow in search of her mother. From that moment on, adventures begin in her life. The adventures are funny on the one hand, and instructive on the other. Arriving in Moscow, Lerka finds a very strange baby in her mother's house. It turns out that Mom was taken to the hospital, and six-year-old Deniska is none other than little Lerkin's brother. Deniska is a very unusual kid, smart beyond his years, but he doesn't talk at all. Two weeks spent in the capital, a difficult relationship with his brother, meeting new people completely change Lerkin's life.