In the kingdom of Mir, a medieval Slavic world surrounded by mountains, an orphaned youth named Nevsky emerges from a mysterious cave with wisdom and powers beyond his years. He raises a young girl abandoned by her village parents, and holds court with the monarch of Mir, Tsar Leo, and its religious leader, Bishop Tserkov. Assisted by a magical talking owl, Nevsky battles the devil himself, and tries in vain to keep the kingdom from being split between Leo's twin sons.