The little girl Sonya dreams of a new construction set, like other children. Her toy box is full of parts from different sets inherited from her older sister and brother. One December evening, a girl decides to write a letter to Santa Claus so that he will help her fulfill her dream. The next day, a new boy, Vadim, appears in kindergarten. He is different from the other children, and therefore no one wants to be friends with him, except Sonya. It is thanks to this acquaintance that the girl makes important discoveries about the nature of friendship and the value of different people in life. But the question remains, will what little Sonya asked of Santa Claus come true?