Vindice and Hippolito enter with the Duke’s corpse dressed up in the pander’s clothes. They position the dead man to appear as if he is in a drunken stupor. Vindice is frustrated because he craves immediate vengeance against the Duke's son but knows that Lussurioso will not come to this appointment alone. Hippolito advises his brother to be patient.
Lussurioso enters, eager to watch Vindice kill Piato the pander. The brothers point out the “man” on the floor and Lussurioso instructs Vindice to kill "the pander" even though he is drunk and asleep. Vindice counters that this might not be wise because drunk men go to hell, but, amused, he complies with Lussurioso's wishes and stabs the body.
Lussurioso soon realizes that the victim is actually his father's corpse dressed in Piato's clothing. Shocked and enraged, he cries out that Piato has killed his father and disguised the corpse in his clothes. Lussurioso informs the brothers that he will call the nobles, the Duchess, and Spurio, but he plans to claim that he found his father dead in order to avoid any further scandal (since Lussurioso was, in fact, trying to commit murder). Vindice says to himself, “Thus much by wit a deep Revenger can, / When murder’s known, to be the clearest man” (126).
Lussurioso notices that his father’s lips have poison on them, and Vindice pretends to be shocked. Ambitioso, Supervacuo, the Duchess, and Spurio enter and all of them express their despair. Spurio says to himself, “Old dad dead? / I, one of his cast sins, will send the fates / Most hearty commendations by his own son” (127). Lussurioso calls for the noble that had previously told him his father was alive and rode forth and condemns the man to death for this oversight. Vindice knows that the nobleman is innocent, but he does not despair over the man's fate. Instead, Vindice comments cynically, “Who would not lie when men are hanged for the truth?” (127). Hippolito and Vindice privately express their pleasure about how well their plan is unfolding.
The nobles inform Lussurioso that he now stands to inherit his father’s title, but he claims to be too grief-stricken to discuss succession. However, he says privately that he welcomes these “sweet titles” (128) and newfound power. The nobles call for the group to prepare for the revels celebrating Lussurioso's ascension to the Duke's throne. Lussurioso decides that his first act as Duke will be to banish his stepmother. He and the others depart, except for Supervacuo and Ambitioso.
Lussurio's stepbrothers bitterly proclaim that Lussurioso shall not outlive the next moon, and decide that Spurio will next. Supervacuo exits first. Alone, Ambitioso sneers that Supervacuo will never be Duke, either.
Vindice, Hippolito, Piero, and a few other lords enter. Vindice calls for the lords to “blast this villainous dukedom vexed with sin; / Wind up your souls to their full height again!” (130). Vindice's audience is intrigued by his proclamations and listen closely as he explains his plan. They will all go to the revels dressed in masks and costumes with their swords carefully concealed. Then, after making sure all of the Duke's guards are drunk, these masked Revengers will kill the Duke and his men.
Lussurioso is crowned Duke, after which the court prepares to celebrate. Joyous music plays and a banquet is laid out. The Duke and his nobles sit at the banquet table. A shooting star appears in the sky.
The nobles surround the new Duke and shower him with compliments, but Lussurioso ignores them and speaks to himself. He has banished his stepmother and now, he plans to kill Spurio and his stepbrothers. He then notices the shooting star and identifies it as a bad omen because “when stars wear locks, they threaten great men’s heads” (152). Lussurioso's nobles placate him by assuring him that his subjects love him and that he will certainly live a long life.
Everyone sits, and the revels begin with a dance performed by the Mask of the Revengers. Unbeknownst to their audience, these four masked men are actually Vindice, Hippolito, and the two other lords in disguise. Lussurioso is impressed with their costumes and privately comments that his half-brother and stepbrothers will soon be dancing in hell.
During the dance, the masked Revengers pull out their swords and kill the Duke and all the men seated at his table. Thunder sounds. Vindice cries out in triumph. Hippolito urges his brother to flee, but Vindice insists on staying behind. He crows, “No power is angry when the lustful die: / When thunder claps, heaven likes the tragedy” (133).
Then, another group of masked revelers enters, comprised of Ambitioso, Supervacuo, Spurio, and an unnamed fourth man. Lussurioso is dying on the ground, groaning accusations of treason. Meanwhile, Ambitioso and Supervacuo are astonished to find that Lussurioso and his men are already dead - as they had been planning to carry out these murders themselves. Nevertheless, Supervacuo boldly proclaims that now he is the Duke, thus angering Ambitioso. Ambitioso immediately slays Supervacuo, Spurio kills Ambitioso, and the fourth lord slays Spurio. Vindice, Hippolito and their two companions return (out of disguise) and feign shock upon seeing the deadly scene.
Antonio enters with a guard and Hippolito urges him to grab the fourth lord. Antonio is momentarily flummoxed by the carnage, describing it as a “piteous tragedy” (134). Lussurioso, who is barely alive, identifies the "men in masks" as his murderers. Vindice quickly blames the fourth lord, who is the only remaining member of the masked troupe. As the guards take away the accused, Vindice cannot help himself - he stoops down and whispers in Lussurioso's ear that he, Vindice, is responsible for the murders of both Lussurioso and the Duke. He jokingly implores Lussurioso to "tell nobody" moments before Lussurioso dies.
Hippolito tells Antonio that the hope of Italy now lies with him. Antonio accepts this grave responsibility with humility. Vindice announces that the rape and death of Antonio's wife have finally been avenged. Antonio comments that it must be a result of "the lab above," but even then, he wonders who murdered the Duke in the first place. Vindice cannot help himself, and blurts out that he and his brother are the ones who killed the old Duke.
Antonio immediately calls for the guards to seize Vindice and Hippolito, which shocks the brothers. Vindice cries out that Antonio has benefited from their plotting, but Antonio is too shrewd to fall for Vindice's promises. "You that would murder [the old Duke] would murder me," (136) Antonio comments. Vindice suddenly laments his spontaneous confession, saying, “This murder might have slept in tongueless brass, / But for ourselves, and the world died an ass” (136). Guards lead Vindice and Hippolito away to be executed. Antonio hopes that their deaths will eradicate any lingering treason from the kingdom.
The Revenger’s Tragedy ends with a rapid escalation into violence in which nearly all of the male characters die or are sentenced to death. Gamini Salgado suggests that this heightened display of depravity is a fitting end for a kingdom that has always been beyond redemption. “In its climactic scene [the play] has a frenetic, panic-stricken kind of rhythm, the pulse-beat of a world rushing headlong to its final and inevitable annihilation,” he writes. Antonio, the only man who displays any virtue in the play, ultimately ascends to power. Contemporary readers may question Antonio's purported virtuosity because of his misogynistic statements in Act I, but his perspective on gender is ultimately a product of the times. Antonio aspires to cleanse the kingdom of all corruption and wickedness, including acts of vengeance. Even though Vindice is right in saying that Antonio has benefited from his treachery, Antonio condemns Vindice for taking the law into his own hands.
Throughout the play, Nature disapproves of the decaying morality in this kingdom. In Jacobean literature, it is common for the natural world to revolt against the machinations of corrupt characters. For example, in Shakespeare’s Macbeth, the stars veil themselves and the horses break loose in wild fear as a result of Macbeth’s treachery. As Lussurioso begins his ill-begot reign as Duke, he is terrified at the sight of a blazing star. He cries out that he is “not pleased at that ill-knotted fire, / That bushing-flaring star: am not I Duke?” (131). He explains, “when stars wear locks, they threaten great men’s heads” (132). Other characters also allude to the belief that Nature responds to the state of human affairs. After pretending to seduce his own sister and mother, Vindice laments, “Why does not heaven turn black, or with a frown / Undo the world? Why does not Earth start up / And strike the sins that tread upon it?” (74). Later he says of the treacherous Lussurioso, “Has not Heaven an ear? Is all lightning wasted?” (114).
The term “Heaven” also raises the question of what role, if any, God plays in The Revenger's Tragedy. While the plot is rife with sin: lust, murder, obsession, revenge, rage, and deception, there are also many mentions of God. Antonio’s wife dies clutching a prayer book, Vindice evokes angels to protect Castiza’s honor and accuses his mother of having the devil in her, and multiple characters speak of heaven and hell. The characters' fates also align with the Christian tenets of salvation and original sin. Castiza maintains her chastity, Gratiana begs forgiveness for her brief moral lapse, and Antonio refuses to pardon murder, even if it is rooted in vengeance. All three of these characters survive. The critic Larry S. Champion ascribes the play's frequent religious allusions to a “value structure so firm that many critics have claimed a missionary tone and a moral fervor.” However, it is important to note that Middleton wrote The Revenger's Tragedy during an era in which culture and religion were very closely intertwined. In that context, it is unlikely that Middleton intended to convert anyone with his words - the religious images are more likely a reflection of the Bible's cultural pervasiveness.
Spurio appears to be an important character at the beginning of the play, but he only appears in the final act for a moment - he kills his stepbrother and moments later, dies at the hands of a nameless man. Despite the lack of character development, Spurio's fate has been sealed since his first appearance. The play implies that because Spurio is a bastard, he is innately dark and twisted. During Junior's trial, he mutters to himself, “And if a bastard’s wish might stand in force, / Would all the court were turned into a corpse” (50). Later, Spurio coldly agrees to sleep with the Duchess to shame his father, whom he hates for conceiving him in the first place. He claims, “Duke, thou didst do me wrong, and by thy act / Adultery is my nature” (55). He thinks of himself as one of the Duke’s “cast sins” (127). In the world of The Revenger's Tragedy, Spurio's mere existence is a physical representation of the disease and corruption that has afflicted this kingdom. Therefore, Spurio must die in order for the kingdom to be cleansed.
"Bastard" is an outdated term that, while still offensive, does not carry the same implications of sin and wickedness as it did during the Jacobean era. Scholar Michael Neill points out, “'Bastardy' constituted a form of adulteration because it was the fruit of forbidden mixture, polluting the ‘pure’ blood of legitimate descent; and it was interpreted as a form of genealogical counterfeiting because it threatened to displace the ‘true’ heir with a ‘false’ and debased substitute.” In addition to (or as a result of) being a bastard himself, Spurio also becomes the physical embodiment of the belief system that Neill describes. He plots to sleep with the Duchess, thus cuckolding his father, the Duke - enacting the same sin that led to Spurio's own conception.
Neill also observes that The Revenger's Tragedy is “obsessed with issues of paternity and succession in which virtually all of its characters are entangled.” Vindice and Hippolito begin on their fateful path towards vengeance after the disgrace and eventual death of their father. Without legitimate patrimony, their entire family hovers on the precipice of sin. Without her husband, Gratiana is no longer a wife but a middle-aged fallen woman who is easily seduced by promises of wealth. Castiza retains her physical virtue, but without a father she will never be able to marry legitimately. Ambitioso, Supervacuo, and Junior are not officially bastards but as stepsons, they are “allotted a structural position closely parallel to that of Spurio in the undermining of patriarchal inheritance and possession.” Lussurioso does not kill his father, per se, but is quick to grab power as soon as he can. Thus, all of the men in the story who lack legitimate patrimony die as part of the moral "cleansing" process.