Act 2 opens in the home of Francisco de Medici, who is the Duke of Florence and Isabella's brother. On stage are Francisco, Isabella, Cardinal Monticelso, Marcello, Giovanni, and little Jacques the Moor.
Francisco asks Isabella, who has just returned to Rome, whether she has yet seen her husband, the Duke of Brachiano. When she says she has not, Francisco jokes that Camillo should burn his house down to destroy the lecherous hangers-on that surround it. It is unclear whether he means to implicate Brachiano as one of those hangers-on.
Giovanni, Isabella and Brachiano's son, reminds his uncle Francisco that he promised him a horse, and Francisco repeats his promise. Marcello, Vittoria's brother and Francisco's attendant, announces that Brachiano has arrived. Isabella pleads for her brother to be kind to her husband, and then exits, after which Francisco orders Marcello, Flamineo, Giovanni, and his servant Jacques the Moor to follow.
When Brachiano enters, Francisco asks Cardinal Monticelso to speak for him, and Monticelso chastises Brachiano for neglecting his throne for an illicit affair. He explains that such behavior tarnishes his public reputation, and then vaguely threatens Brachiano. Francisco then joins the lecture, calling Vittoria Brachiano's prostitute, and threatening war if his brother-in-law does not remedy the situation. Brachiano grows contemptuously assertive, warning Francisco that he would win any such battle. Francisco then insists Brachiano will soon realize that Vittoria is a prostitute when his hair falls out from venereal disease.
At that moment, Giovanni enters, dressed in a suit of armor. Monticelso further suggests to Brachiano that the boy needs a virtuous role model in his father. Giovanni asks for a pike, and explains to them that if he were the leader of an army, he would put himself on the front lines to set an example for his men. Faced with the boy's earnestness, Brachiano and Francisco appear to reconcile.
Isabella enters again, and Francisco, Monticelso, and Giovanni exit. Brachiano remarks on Isabella's good health, and asks what brought her to Rome so hurriedly. Isabella explains that she returned from devotion, which Brachiano interprets as religious devotion, but which Isabella means as marital fidelity. She suggests that they must pray for the forgiveness of Brachiano's sins, which angers him. He tells her to go to her room, but she begs him for a kiss. He accuses her of being jealous, which she denies. When he draws near to her mouth for a kiss, he recoils from her bad breath. He accuses her of forming conspiracies against him with her family, and of having had an affair with a young man in Rome. Against Isabella's protestations of love, Brachiano insults Francisco as a fat fool, and he curses their marriage and their son. In a parody of traditional marriage vows, he divorces Isabella on the grounds of her supposed infidelity. Isabella warns that she will die and soon ascend to heaven without him, but she also offers to take public responsibility for the divorce on the grounds of his actual infidelity and of her jealousy, which would make him look slightly better to society.
Francisco, Flamineo, Marcello, and Monticelso re-enter the room, where Isabella is now playing out the divorce. To the men, Isabella appears jealous and vengeful, threatening Vittoria and calling her a a whore. She repeats Brachiano's divorce vows as Francisco looks on increduously. Seeing Isabella as a jealous woman, Francisco tells her that she deserves her cuckold's horns, and Isabella threatens to leave immediately for Padua. Francisco protests, but Brachiano encourages the plan. To herself, Isabella mourns the loss of her marriage and her breaking heart.
Camillo enters, and while Francisco is distracted by business, Flamineo plots secretly with Brachiano to kill Camillo and Isabella. Flamineo introduces Brachiano to Doctor Julio, a quack doctor and criminal who will gladly help poison Isabella in Padua. Further, they can arrange for Camillo to die that night of an apparent accident. Pleased with their plans, the three men exit.
Monticelso explains to Camillo how an emblem, or allegorical drawing, has been thrown at him. The picture is of a horn-less stag weeping, with the saying that "plenty of horns hath made him poor of horns." Monticelso interprets the picture as proof that Camillo has been cuckolded, and Francisco then tells him the story of Phoebus, the sun god's, marriage. When Phoebus was to be married, all the humans begged the other gods to castrate Phoebus, explaining that one sun already caused too much heat. If Phoebus were to have children, life would become unbearable. Francisco warns Camillo that if Vittoria reproduces, all of humankind will suffer from her progeny, and advises him to leave to go fight the pirates who currently plague Rome. Camillo worries that his absence may only inflame the adultery, but Monticelso promises to watch Vittoria in his absence.
Camillo and Marcello then leave, at which point Francisco and Monticelso admit that they send him away in order to test Brachiano. Monticelso reveals that Lodovico, the rumored pirate, is actually in Padua, and wants to plead with Isabella to help him overturn his banishment. He explains that although it may seem dishonorable to deceive his nephew Camillo, he would rather hurt Camillo in order to avenge him, than let the wrongs against Camillo go unavenged.
Brachiano and a Conjurer enter in the dead of night. Brachiano begs the Conjurer to reveal how his murder plans are unfolding, and the Conjurer insists that he usually avoids dark deeds, as he hates being called a "nigromancer." However, because Brachiano has paid him, he will fulfill the request.
A dumb show - action performed in pantomime - is enacted on one side of the stage. Brachiano watches as Doctor Julio and Christophero creep suspiciously into Isabella's bedroom. They pull aside a curtain to reveal a portrait of Brachiano. They put on protective glasses and cover the portrait's lips with poison, and then leave, laughing. Isabella then enters the room, followed by Lodovico, Giovanni, Guid-Antonio, and unnamed others. She prays before the painting, and then kisses it three times. Almost immediately, she faints and dies.
Brachiano is pleased with the vision the Conjurer has shown him, and the Conjurer explains that Doctor Julio concocted that plan after noticing Isabella's habit of kissing the painting. When Brachiano asks why Lodovico was there, the Conjurer explains how Lodovico passionately dotes on Isabella.
The Conjurer then conjures up the second dumb show, this time on the other side of the stage. Flamineo, Marcello, Camillo, and several unnamed captains enter, and carouse a while before someone fetches a vaulting-horse. Marcello leaves the room, while Flamineo and Camillo strip their clothes off in order to vault. Camillo is about to vault when Flamineo breaks his neck and then arranges the body to suggest Camillo died while vaulting. Flamineo calls for help, and Marcello rushes in with Francisco and Monticelso. The Duke and the Cardinal apprehend Flamineo and Marcello, and then leave, seemingly to also apprehend Vittoria.
Brachiano thanks and pays the Conjurer for showing him the murders, and the latter cryptically warns that "great men do great good, or else great harm."
In this Act does the meaning behind the play's title become more apparent. In the first scene of Act II, Jaques the Moor, who would have been a black African, stands silent as a visual shadow of the great white men present, including Francisco and Monticelso. The title of the play suggests the importance of color in determining guilt. White, usually associated with innocence and virtue, instead aligns itself with vice and sin. In Jacques's presence, we see a visual reminder of the darkness lurking behind the "white" facades of such great men as Francisco and Monticelso. Although these men are ostensibly on the side of the law, their private actions suggest that each of them may be as much of a villain as Lodovico or Flamineo. It is in keeping with the play's many ironies that the traditionally pure "white" should hide darkness and sin.
Francisco's power is extremely apparent. The stage is crowded at the Act's opening, but Francisco clears it with a simple order. This is a startling visual display of his power, as well as an echo of Act 1, Scene 1. Similar to that earlier scene, this one features two men chastising a third for his immoral actions. Francisco criticizes his brother-in-law Brachiano, and uses the threat of war as a tactic. Their overly aggressive, masculine displays are ceded by the arrival of Giovani, who implicitly shames them by suggesting the chivalric masculine behavior of protecting his men as a hypothetical army captain. Giovanni is a visual representation of what Brachiano should be striving for - the chivalric values of virtue and courtly love.
Like each Act of the play, Act II features several scenes of irony. One of the most notable is the divorce scene, which parodies a marriage ceremony even as it dissolves a union. Isabella is the wronged person, yet she offers to play the martyr. She is the only one with an actual cause, and yet offers to facilitate a divorce she could oppose. All of her virtue ironically pleads Brachiano's case to the audience, however; her excessive sanctimony helps us understand why her husband would prefer a sensual lover to his prim, overly-religious wife.
The irony is compounded as soon as Monticelso and Francisco re-enter, and Isabella acts like a jealous shrew for the sake of her husband's happiness. The misogyny of this world is also apparent in this scene, as Francisco calls his sister a "foolish, mad, and jealous woman" for her displays. A woman's jealousy is enough cause for a man to request divorce, though a woman's knowledge of a man's infidelity would not necessarily prove just cause. Isabella is limited in her agency, and is only able to reach a desired end through manipulation, creating a scene that is not as it seems.
The play's pessimistic view of humanity is quite apparent after Isabella leaves, and Camillo and Julio enter. The six men on stage divide into two groups of three, establishing a "split-stage" that highlights parallels and contrasts between the two groups. In each case, two characters concoct a plot that is to be enacted by the third. Flamineo and Brachiano plot to kill both Isabella and Camillo with the help of the mysterious Doctor Julio, while Monticelso and Francisco manipulate Camillo into leaving, so that they may observe Brachiano's behavior. While Monticelso and Francisco are ostensibly working on the side of virtue and the law, they employ treachery just as deviously as Brachiano and Flamineo. Ironically, their pursuit of virtue reveals their moral limitations. Monticelso addresses this contradiction, by suggesting that revenge is most important - he would rather gamble with Camillo's life by sending him out to sea than let his nephew be made a fool of. Yet again, reputation trumps most other qualities, and the pursuit of it causes all characters to reveal their vice.
Webster's plays reveal their innate theatricality in performance, and the dumbshows created by the Conjurer are quite delightful to see. However, they also possess much literary value. Isabella's death is a foreshadowing of Brachiano's own, which occurs through a poisoned mouthpiece, as well as a reference to how Brachiano divorced her with a kiss. Camillo's death conforms somewhat to the historical record, in which Francesco Peretti, his historical counterpart, was murdered at Monte Cavallo, literally "horse mount." The activity also serves as a sexual pun, however, since vaulting can imply sexually mounting, and Camillo's placement underneath the vault highlights his sexual impotency.
Finally, the Conjurer's assessment at the end of the Act provides insight into Webster's sense of humanity. By noting that great men do either great or terrible things, he indicates that people are rarely pure in their virtue or vice, but rather easily led to devote their potential to either or both. The "great" man might do the worst things, and cannot be understood simply by his outward appearance. Likewise, sometimes the man who does "harm" is in fact "great." What we are capable of is not always apparent, in the same way that morality is not always contained in white.