Fantaghirò, the king's daughter, born during a relentless war, is unwanted and marked by her mother's death. Her father, desperate for a male heir, considers sacrificing her until a witch intervenes, foreseeing her extraordinary destiny. As she matures into a beautiful young woman, her father ages while the war continues, now led by young King Romualdo. Influenced by a ruthless general, he offers his three daughters to distant princes in hopes of securing victory.

Fantaghirò confronts King Romualdo, who thinks she resembles the nymph he loved in the forest. To verify her identity, he plans to test her, and she accepts. As their duel approaches, Romualdo is increasingly captivated by her, while Fantaghirò struggles with her own feelings. When she has the chance to win, she hesitates to strike the prince and flees, overwhelmed by love.

As she prepares for her wedding to King Romualdo, Fantaghirò leads her soldiers against bandits led by the fearsome Occhiodoro. Her sisters, Caterina and Carolina, are married to Ivaldo and Cataldo. As a wedding gift to Romualdo, Fantaghirò promises to never wield a weapon again, a vow magically sealed by the White Witch. Unbeknownst to them, the Black Witch is scheming against Fantaghirò and her kingdom.

Fantaghirò sneaks into the Black Castle and confronts the Black King, armed only with a stone. Unbeknownst to her, he is her true love, Romualdo. As they fight, she tries to reveal her identity but fails. Just before defeat, she calls on the White Witch to break her vow. Meanwhile, Fulmine and Saetta, tired of the Black Witch's deceit, create a potion to put her to sleep, enabling Romualdo's men to escape under Fantaghirò's command.

Once upon a time, there was a wicked sorcerer named Tarabas, who lived in an underground kingdom with his fearsome mother, the witch, Xellesia. Young and handsome, Tarabas learns that a child born to a king will one day defeat his cruelty. In a panic, he sends his army to hunt down all the king's children under ten, even attacking the castle where Princess Fantaghirò and Prince Romualdo are preparing for their wedding.

Fantaghirò and Smeralda meet a handsome young man named Tarabas, who offers to guide them to Fantaghirò's castle. He hides his true identity and falls for Fantaghirò, but when he tries to kiss her, he transforms into a hideous beast. The next day, they discover Tarabas has disappeared. As they continue their journey, Tarabas's knights ambush them and kidnap Smeralda. Just in time, Tarabas intervenes, defeats his knights, and rescues Smeralda.