Based on Samuel Shellabarger's novel, a peasant pretends to be an aristocrat and serves Cesare Borgia but falls in love with a countess.
In Rome in 1500 Cesare Borgia (Orson Welles) attends the funeral of his sister Lucretia's husband. Cesare wants to take Ferrara and sends Andrea Orsini (Tyrone Power) to arrange a marriage for Lucretia. Orsini gives a painting to Camilla Verano (Wanda Hendrix), and she gives him a ring.
Mario Belli (Everett Sloane) tries to stab Orsini for D'Este; but Orsini disarms him, and he agrees to accompany Orsini. On the way Orsini visits his peasant mother (Katina Paxinou), who dislikes his ambition. Belli introduces Orsini to Alphonso D'Este in Ferrara, and Orsini shows him a portrait of Lucretia. Alphonso agrees to wed her for 200,000 ducats.
Cesare suggests that Orsini go after the wife of the elderly Count Marc Antonio Verano (Felix Aylmer) and introduces them. Cesare pays Belli 200 ducats for serving him. Orsini goes to Verano's castle and announces he is spying on their loyalty. Camilla warns him not to harm her husband. Orsini paints a portrait of Belli, and she admires it. Count Verano asks Orsini to do a portrait of his wife, whom he trusts to tell him of an affair. Camilla likes the painting he does.
In the spring Orsini is anxious. Count Verano says that Cesare has requested troops. Orsini asks Belli if he could kill the Count but stops him. Count Verano says that Cesare is evil, and he refuses to help him; but he lets his people decide. Belli withdraws from Orsini, who offers his sword against Cesare. Count Verano and Orsini lead cavalry and charge. The Count is wounded, but they win the battle. The dying Count asks Orsini and Camilla to be true to each other.
Cesare attacks the castle with catapults and cannons. Soldiers climb ladders and face hot oil. After three months Orsini tells Camilla they can no longer hold out, and he wants her to escape. Don Esteban and Belli come to negotiate, but Camilla refuses to hand over Orsini to Cesare. That night Orsini lets himself be captured and persuades Esteban to give Camilla the terms in writing.
Cesare comes to Camilla, who asks for Orsini. At a banquet Orsini is presented as a beaten peasant in chains. Camilla tells Cesare that she loves Orsini. His mother is brought in and recognizes her son. Orsini says power has no victory but is hated. Cesare sentences Orsini to starvation, but Belli is given permission to gouge out his eyes. Belli tells Orsini to scream and thus saves his life. Cesare leaves.
Belli tells Orsini that Esteban has Camilla imprisoned in the castle. Orsini organizes a revolt. First he enters the castle to rescue her. He kills a guard, and Esteban has the bells rung. Orsini defeats Esteban in a sword duel, and others accept him. In the final scene Orsini weds Camilla.
This drama of political intrigue and romance reflects
the treacherous power relationships of Renaissance Italy. The
ethics of the Borgias are contrasted to the conscientious Count
while Orsini and Belli waver in between and switch sides.