Act 4, Scene 1
Barabas and Ithamore gloat over their success in poisoning the nuns. The Jew expresses particular satisfaction over his daughter's death. Friar Jacomo and Barnardine enter and, after a series of interrupted exchanges, intimate that they know of Barabas's hand in the deaths of Mathias and Lodowick. Barabas realizes that his daughter has confessed. He immediately puts on a show for the two friars: dissembling great sufferance under the burden of his many sins, he expresses a desire to convert to Christianity himself. He ostentatiously adds that he still possesses a large fortune, pointing out that this fortune would be donated to the monastery into which he enters.
At this point, the two friars start bickering over which monastery Barabas should choose. Once Barabas tells friar Jacomo to visit him at one o'clock that night, the two friars break into a fight. Barabas pulls them apart and asks Barnardine to leave with Ithamore. In his usual duplicitous manner, he has promised his favors to the friars while plotting to murder both of them. One, after all, converted his daughter to Christianity, and the other knows enough to have him condemned to death.
Ithamore returns after leading Barnardine into the house, noting that the friar has fallen asleep with his clothes on. The master and slave tie a noose around the friar's neck and strangle him on the spot. They then prop up his body against his staff and wait for Jacomo. When the friar arrives at the promised hour, he finds Barnardine standing silently in his path. Friar Jacomo decides to force his way past his former friend and strikes him with his staff, whereupon Barabas and Ithamore jump out of hiding. The two accuse Jacomo of murder and lead him off to be tried by the law.
Act 4, Scene 2
Pilia-Borza enters, telling Bellamira that he took her letter to Ithamore. Ithamore enters and delivers a monologue recounting Jacomo's calm behavior at the gallows. As he wonders aloud why Bellamira has summoned him, he arrives in front of her house. Bellamira welcomes him with sweet words and a kiss, and he decides that he should steal some money from Barabas to make himself presentable. He discusses the possibility with her and Pilia-Borza, then agrees to write a blackmail letter to Barabas for three hundred crowns. While Pilia-Borza delivers it, Bellamira pretends to think little of the gold and continues to play the seductress. Ithamore would be glad to marry her; he bursts into uncharacteristic high poetry. Pilia returns with the money, which inspires Ithamore immediately to write a second letter for five hundred crowns more, plus one hundred for Pilia.
Act 4, Scene 3
Barabas enters reading over Ithamore's first letter. As he expresses his outrage, Pilia-Borza enters carrying the second letter demanding five hundred crowns. Barabas invites Pilia-Borza to dinner in hopes of poisoning him, but the latter will hear nothing till he sees the money. The Jew finally gives in, wincing at the sight of so much gold leaving his pocket-but puts on a show for Pilia-Borza, lamenting his betrayal by Ithamore more than its financial consequences. Alone again, Barabas genuinely feels the hurt of the betrayal but focuses on the money and the possible consequences of being found out. He resolves to visit Ithamore in disguise, hoping to rid himself of the blackmailers.
Act 4, Scene 4
Bellamira and Ithamore drink wine while exchanging amorous words. Ithamore boasts of the evil deeds that he has committed with Barabas, upon which Bellamira and Pilia-Borza decide to betray him to the governor, after blackmailing him further. The Jew himself enters the scene, dressed as a French musician. Barabas presents the three blackmailers with poisoned flowers to smell, and Pilia-Borza pays him two crowns to play the lute. Ithamore asks him if he knows the Jew named Barabas, and Ithamore proceeds to rail against his master with false claims about his eating and dressing habits. Barabas then leaves the scene under the excuse that he feels ill--perhaps disgusted by the filthy lies that Ithamore has been telling about him.
As the scene ends, the three agree to send a third letter demanding one thousand crowns. Ithamore defends their blackmail with an anti-Judaic justification, speaking the last line of the act: "To undo a Jew is charity, and not sin."
When the friars visit Barabas's house, their express purpose is to urge him to repent of his sins, but they have very little leverage over the Jew Barabas. Since his murder of Mathias and Lodowick was revealed to Friar Barnardine in a confession, the friars may never speak of the matter in public, so even if they wanted to blackmail him, they could not do so without losing their own standing. Even addressing the matter to Barabas may transgress the sacred rules. Their presence does not really concern Barabas, who has already embarked on a killing spree to conceal his crimes. He may also be rather paranoid by now. Still, he has the cunning to solve the problem by finding an excuse to turns the friars against each other.
The friars could hardly be happier with his offer of his fortune. At the first mention of it, they seem to forget their spiritual values and instead try to draw him to one monastery or the other on material grounds: for example, one must go barefoot in one of the monasteries, as the other friar charges. Only moments ago, they were preaching to Barabas to repent, so their quick turn of motivation to money emphasizes their hypocrisy. As for Barabas, in his usual cunning manner he plays both ends against the middle, pondering the best way to murder them.
As with the case of Mathias and Lodowick, his plot is realized almost effortlessly. The first murder is of a sleeping Barnardine. Then, blinded by his desire for gold, Jacomo strikes the already-dead Barnardine and involuntarily completes the perfect murder. Again Ithamore has a central role in this plot.
Ironically, Barabas invokes the particulars of the law to have the friar tried:
The law shall touch you, we'll but lead you, we.
'Las, I could weep at your calamity.
Take in the staff too, for that must be shown;
Law wills that each particular be known. (IV i 205-9)
The trope of a Jew enforcing the laws of the Christian commonwealth with the intention of causing a tragic consequence is repeated with Shylock in Shakespeare's The Merchant of Venice.
Forces of avarice and desire come in multiple degrees in The Jew of Malta. Whereas almost all of the characters are obsessed with gold, Ithamore finds a formidable rival to the lustrous metal. At first sight of Bellamira, he falls head over heels in love. Even before the courtesan prompts him, Ithamore resolves to steal Barabas's gold. Also, Ithamore gives Barabas a taste of his own poison through blackmail, and the slave is in turn being manipulated by Bellamira and Pilia-Borza. (Bellamira's phrase "'Tis not thy money but thyself I weigh" echoes Lodowick's earlier words concerning Abigall.) The two conspirators resolve to notify the proper authorities only after they have made their fortune.
These recourses to political authority are ironic in that Ferneze is no model citizen. He represents the corruption of the island, and it is his corruption that set the drama in motion from the beginning. Neither the church nor the state, at least as they are embodied in hypocritical representatives, has sufficient moral authority to enforce the laws. Nevertheless, justice (like everything else in the play) is swift. It is hard to believe that Friar Jacomo is so dense as to believe that he killed Friar Barnardine with his staff, but he apparently accepts the judgment of the Jew and his slave to the degree that he goes willingly to the gallows and the afterlife. The state apparently accepts such testimony and then goes straight to the execution.
As for Barabas, he twice pays the amount exacted by Ithamore. At this point, it is not clear that the Jew has all his wits about him. Ithamore's blackmail carries little force, because if Ithamore were to confess the truth as he threatens, he also would probably be jailed or executed, and Barabas's fortune probably would be seized once again by Ferneze and his officers. This threat is therefore more or less empty, yet Barabas complies. Barabas might be stuck, however, now that others are in on the news.
Why does Barabas comply with the blackmail? Is he weary, paranoid, or simply careless? Or is the money amount too small to be concerned with? He can afford to pay now, without revealing his plot of killing Ithamore until later. Barabas certainly has money enough to buy time. Having purchased some time for strategic reflection, he arrives in disguise at Bellamira's house in the last scene of the act, with consequences that will become clear in the final act.