In an ordinary small town lives an unusual girl, Katya, who is almost nine years old. The girl herself thinks that everything is fine with her, and it just so happens that she is very serious and always turns out to be right. Katya loves to teach everyone who happens to be nearby: her mother Olya, her father Volodya, her grandmother Galya, her classmates, and even her cat Barsik. But one day the girl’s eyes are opened to her character not by anyone, but by Barsik. And from this day on, Katyusha’s measured life ends, and she is increasingly occupied by the question: how can she learn to laugh? The story is intended for children aged 5-10 years.