Tragic news for the Borgia family is followed by a shocking revelation from Cesare; Lucrezia surprises herself by falling for a new suitor, Alfonso of Aragon, and accepts his proposal of marriage; Cesare tortures the rebel leader Savonarola but can't extract a confession, so he fakes one and burns the heretic; the assassin finally strikes with a poisoned chalice of wine.

Alexander VI refuses to allow a Catholic burial for Paolo, despite his doubts about the stable boy’s suicide, causing Lucrezia to embark on a hunger strike that threatens the life of her infant son; the French army heads back to Rome, allied with Sforza; Della Rovere slips back into the city unnoticed to launch a plot against the Pope’s life.

It's Easter and Alexander makes plans for a celebration to end his pious fast even as Della Rovere's assassin ascends to the position of the Pope's taster. Lucrezia's lover asks for her hand in marriage but her father dismisses him and his request. Juan's wild behavior threatens the life of Lucrezia's child, forcing Cesare to make a chilling decision about his brother.

Pope Alexander fights for his life; the cardinals fight for control of the papacy; Cesare and Micheletto track the assassin; Della Rovere prepares to make his move.

Micheletto returns to Cesare briefly to help him destroy the walls of Forli and capture Caterina Sforza and later recruit her assassin Rufio.

Cesare deals with the cunning Sforzas decisively; Alexander disguises himself and travels to Florence to hear the fiery preacher Savonarola, not realizing that Della Rovere is trying to recruit the rebellious holy man to his cause.

Lucrezia escapes with Alfonso and her baby from Naples while the Pope corners the market in sulfur, restricting others from manufacturing gunpowder.

Juan returns to Rome trying to spin his combat injury as proof of his valor, but Cesare exposes his brother's ignoble behavior; Lucrezia takes a lover in her intended husband's younger brother; Della Rovere has recruited an angel-faced young friar as his suicide assassin, and the young man advances their agenda with a bold move against the Pope's food taster.

Juan's triumphant return from Spain is marred by his unsuccessful siege of the Sforza castle; Lucrezia purposely scuttles a scheme to marry her off to a rich Genovese merchant; Savonarola's forces conduct the infamous "Bonfire of the Vanities".

The invasion by King Charles of France and Della Rovere proceeds with victory seemingly inevitable as the French sack the city of Lucca and the Italian powers flee to their banner, with Lucrezia's husband Giovanni Sforza poised to join them in the name of Milan; inventor Leonardo Da Vinci (guest star John Lynch) shows his drawings and blueprints for war machinery to the invaders.

Lucrezia's financially and politically motivated wedding to Milanese nobleman Giovanni Sforza is a disaster thanks to Juan's inappropriately bawdy play in his sister's honor, Cesare's brazen flirting with a married baroness, and the arrival of the Borgia children's illegitimate mother; Della Rovere seeks the aid of the illustrious Medici family and their counselor, Machiavelli.

His coffers depleted by his expensive rise to power, Rodrigo seeks funds through a profitable marriage for Lucrezia that will ally with him Milan, and charges a fee for safe haven in the Holy City to Jews displaced by the Spanish Inquisition; the Borgias host a charming Turkish prince; Micheletto is ordered to rid his patrons of the ongoing threat posed by Della Rovere.

Pope Alexander VI takes a new lover and throws a grand, pagan fete for the citizens of Rome when a cache of ancient artifacts is discovered; the rivalry between brothers Cesare and Juan spills into the streets; Lucrezia tends to her newborn child; now a pastoral priest once again, Della Rovere narrowly escapes an assassination attempt.

Della Rovere reaches France and strikes a bargain with its ruler to invade Italy and install him on the Papal throne in exchange for control of Naples; Rodrigo attempts to thwart the invasion through an alliance by marrying his youngest son Joffre to Princess Sancia of Naples (guest star Emmannuelle Chriqui), but Juan nearly sabotages the plan by seducing his prospective sister-in-law.

Rodrigo successfully bribes and intimidates his way into an election as Pope Alexander VI, making him the new leader of the Catholic Church; powerful Cardinals Della Rovere and Orsini oppose his rise; the Borgias recruit a talented assassin named Micheletto to their cause.

After the French king occupies a deserted Milan, he tasks Cesare with killing Ludivico, and Lucretia becomes involved in Neapolitan palace intrigue.

Alternately neglected and abused by her cruel husband, Lucrezia has an affair with Paolo, a handsome stable boy; Cesare strikes a bargain with Machiavelli: deny French troops passage across his masters' lands in exchange for suppression of Savonarola, a fiery preacher of anti-Medici sermons; in love with baroness Ursula, Cesare takes drastic action to get rid of her husband.

The invaders capture a fleeing and pregnant Lucrezia as they march on Rome, but she charms King Charles and is allowed to persuade her brother Juan to withdraw his hopelessly outmatched defensive troops; Pope Alexander VI awaits to learn of his fate as Charles enters the city and makes his way to the Vatican.