On the eve of Saint Nicholas Day, in a cozy Carpathian hotel, Saint Nicholas and his helpers prepare to fulfill children's wishes. However, they suddenly find a letter that was lost and remained unread for over 30 years. It was written by a boy named Borya from an orphanage, whose wish never came true. The boy grew up and stopped believing in miracles, and with this lost belief, Saint Nicholas's magical power begins to fade. The mistake needs to be corrected before the holiday. Now the helpers must find the adult Boris — the same boy who wrote the letter. But he no longer resembles the child who penned the letter: he’s a cynical and wealthy investor who doesn’t believe in love or family. After a random accident, Boris begins to see a nine-year-old boy alongside him — himself as a child. By the time Saint Nicholas Day arrives, he must fulfill his childhood dream, or he will lose the ability to feel joy forever, and Saint Nicholas will lose his magical power.