The story of a nine-year-old boy Denis, who first enters the circus. The new world captures his imagination. He falls in love with a little actress, an equilibrist — a girl on a ball. After a while, Denis persuades his father to go with him to the circus again. But the performances in Moscow ended, the fairy flew away to another city... Once, being in a museum, he sees a painting by Pablo Picasso "Girl on a Ball". In this picture he recognizes his love — Tanya ....