The film tells about the adventures of eight-year-old Artem, whose family just moved from a big city to the old house in the Carpathians. On the eve of St. Nicholas Day, Saint Nicholas himself appears unexpectedly to Artem. In fact, this is a thief in a Nicholas' suit. The boy, along with the teenage sister and their friends, have to show true cohesiveness, courage and ingenuity, in order to defeat the thief and save the real Nicholas.