In August 1500, Andrea Orsini, Tyrone Power, a gifted young nobleman who is equally adept with brush, blade, words, and charm, serves the Machiavellian prince Cesare Borgia as a soldier. Pleased with Andrea’s ability to follow a plan and keep his eyes fixed on a larger goal, Borgia entrusts him with a delicate intrigue: to arrange the marriage of his widowed sister, Lucrezia, to Alfonso d’Este, the son of the Duke Ercole d’Este of Ferrara. The move is meant to strip Ferrara of its threat to central Italy’s balance of power. Yet this assignment quickly seeds a fierce rivalry with Don Esteban Ramirez, a mercenary captain with his own ambitions, who becomes Andrea’s wary foe.
To fund the mission, Andrea travels to Venice to sell some of his paintings. There he encounters Camilla di Baglione, Wanda Hendrix, the young wife of the aging Count Marc Antonio Verano of Citta del Monte, and he is drawn to her warmth and spirit. He even offers her a painting he hopes to sell for a hundred ducats. The day darkens when an assassin lashes out at him, but Andrea fends off the attack and, sparing the killer’s life, learns who hired him: the Duke Ercole d’Este himself. In a shrewd turn, Andrea hires the same killer, Mario Belli, as part of his growing entourage, betting that a dangerous ally can be tamed by his own resolve and artistry.
On the road to Ferrara, Andrea stops at the farm of a blacksmith’s widow, reputed to guard gold stolen by her bandit son. The widow is actually his mother, and the purported bandit son is Andrea Zoppo, not the noble Orsini he pretends to be. The reunion is tense, as the mother disapproves of her son’s path, but the encounter reveals a deeper motive behind Andrea’s chosen mask. Belli watches from a window, sparking tension and curiosity as Andrea presses on toward his goal. In Ferrara, he uses a mix of intimidation and flattery to win over the aging duke and to flatter Alfonso, securing the marriage alliance Borgia desires.
Andrea’s next mission—again chosen over Don Esteban—is to act as ambassador to Citta del Monte, where the Borgia aims to seize the mountaintop city by spring. He is to use a romantic entanglement with Camilla to pave the way for the “necessary” removal of the elderly count. Yet Borgia secretly has Belli spy on Andrea, reporting if his loyalty wavers. Andrea learns that the old count often retreats to a high precipice to contemplate his people and landscape, a moment that reveals a man’s depth of care. Belli, who relishes the role of a faithful opportunist, is eager for violence, but Andrea’s compassion for the count’s wisdom and love for his people tempers such impulses. Camilla, despite lingering suspicions about Andrea, grows to admire his artistic soul as he paints her portrait, finding in his quiet intensity a kindred spirit.
As the campaign intensifies, Borgia, through Don Esteban, orders the count to allow the army’s passage and to supply troops. The count resists, bolstered by the support of his people. Andrea’s loyalties waver again, but Belli—the self-proclaimed “born traitor”—issues caution and stokes discord, until a different path slowly takes shape. The crucial moment arrives when Mother Zoppo, Katina Paxinou, steps forward to remind everyone of Andrea’s true lineage and the stakes of their struggle. Her testimony becomes a turning point, prompting a reconsideration of the king’s grip on the mountaintop.
With the siege at a turning point, Andrea and Belli forge a plan to free Camilla and rally the people to retake the city. Inside the castle, Andrea’s resolve is put to the test in a brutal clash; he defeats Don Esteban in single combat, only to face a potential second execution at the hands of another officer. The veteran officer Balgioni, weary of endless bloodshed in the name of Borgia, steps in and spares Andrea, recognizing the courage and integrity that has guided him. The uprising spreads, the people seize control from Borgia, and, at last, Andrea and Camilla are united in marriage as their city begins to heal and rebuild.
