In ancient times, the forest of Hercynia was inhabited by nymphs and satyrs, whose beauty was unmatched in the eyes of mortals, and it is said that Marfisa, daughter of the emperor, was no less. To the corners of the world news of this swan's beauty spreads, and four kings are willing to raise armies to conquer her, but Marfisa has eyes for nothing but the forest of Hercynia, for within its borders lie fey mysteries that no one has yet been able to solve. When the green-haired witch arrives at the imperial palaces, accompanied by a mysterious guest wearing a rare fairy ring, fate begins to shake things up, and in a domino effect four kings wage war and long-hidden fairy creatures begin to emerge with good or bad intentions. The Swan and the Fox tells the grand adventure of heroes of the most disparate natures, acting in the name of love and friendship, captured by a fairy ring and its mysterious bearer.