Act I, Scene I
Introduction to the series of events from before the play: death of father and Gloriana. Vindice tells Hippolito he will be the pandar that Lussurioso asks for. It is revealed that the Duchess' youngest son has raped Lord Antonio's wife and Castiza and Gratiana are shocked. They discuss their father's death.
Act I, Scene II
The trial and imprisonment of the youngest son. Ambitioso and Supervacuo say they will free him. The Duchess is angry at the Duke for not freeing her son and so decides to physically act upon her previous affections for Spurio. Once he is convinced they are both revenging him through adultery, making him a cuckold. It is revealed that Spurio hates the Duchess. Duke's past adulterous sins (aka the conception of Spurio) revealed.
Act I, Scene III
Piato is invented. Piato is employed by Lussurioso to get Castiza to be his lover through her mother (he will not marry her because of her low social standing). Vindice is appalled but decides to test his mother and sister's virtues by doing the job.
Act I, Scene IV
Lord Antonio reveals that his wife has killed herself after her rape. He describes the series of events that took place at the masque. Hippolito, Piero and other Lords are very upset and they are all outraged that the Youngest Son has not been prosecuted yet. They all swear to revenge her death and this comforts Antonio.
Act II, Scene I
Vindice as Piato delivers letter from Lussurioso to Castiza who is outraged and hits him. He tests Gratiana and she remains good until money is mentioned and then she agrees to make Castiza agree. Vindice is appalled. They both attempt to make her do it but she angrily disagrees which pleases Vindice. Vindice asserts that women are the source of all sin.
Act II, Scene II
Lussurioso thanks Hippolito for recommending Piato. Piato tells Lussurioso what happened with Castiza and Gratiana. Lussurioso decides to go to Castiza tonight. Hippolito returns and tells Vindice about Spurio and the Duchess's relationship. Spurio hears that Lussurioso will commit adultery and says he will be able to disinherit him and make him bleed soon. Piato reveals Spurio and the Duchess's affair to Lussurioso. He angrily begins towards her chamber with his sword.
Act II, Scene III
Lussurioso charges in on his father and step-mother in bed together. The Duke calls treason and says he will be arrested and killed. Vindice and Hippolito leave- they cannot believe their luck. Spurio enters and is angry that he missed the opportunity to grab Lussurioso before he left to Castiza's but then is happy to discover the events that have taken place. Ambitioso and Supervacuo plead for his release in a way that is clear they don't mean it. The Duke tricks them sending them to say kill him BUT then the Lords enter and plead for his release and along with his plan the Duke sends them to do this. The Duke says he ought to forgive this because he himself has so many adulterous sins in his past.
Act III, Scene I
Ambitioso and Supervacuo decide to pretend they didn't understand their step-father's order to have Lussurioso killed in a few days and say he is to be killed in the morning. They are both selfish and although outwardly working together, also working for their own self-interest.
Act III, Scene II
Lussurioso is freed from prison by the nobles.
Act III, Scene III
Ambitioso and Supervacuo instruct the guards, feigning sadness, to execute their brother in the morning according to (their version of) the Duke's command and then laugh about how clever they've been.
Act III, Scene IV
The Youngest Son receives a letter from his brothers which says he will not have to wait long now to get out of prison. The officers fetch him and tell him he will be executed. He refuses to believe it until the officers provide him with parallel meanings of what his brothers have written. He remains stubborn that the rape he committed was good, even in his last few lines.
Act III, Scene V
Vindice reveals to Hippolito how the Duke has asked Piato to find him a woman. He has dressed up Gloriana's skull and put poison on it. They are in a dark place where the Duchess and Spurio have also agreed to meet. They see the Duke tell his servants to say he is away from court on private business. Piato sends the Duke in with the skull, he is poisoned by kissing it and then the brothers reveal who they are. They force him to watch Spurio and the Duchess, who also insult him, and then they kill him. This means they now have their revenge for both their father and Gloriana.
Act III, Scene VI
Ambitioso and Supervacuo argue over who came up with the idea to have Lussurioso beheaded. The guard brings them the head and they are ecstatic but pretend that they are very sad. Then Lussurioso comes in and thanks them for freeing him. They discover that they have killed their brother and are distraught. The scene ends with Ambitioso saying that they will get revenge by killing Lussurioso.
Act IV, Scene I
Lussurioso tells Hippolito how angry he is at Piato for being put in prison. He then banishes Piato from his sight. He then asks Hippolito to bring his brother Vindice to court, whom he tells the audience will kill Piato. The Lords enter and Lussurioso and the Lords discuss the absence of the Duke and assume wherever he is it is all fine, he is the Duke after all.
Act IV, Scene II
Hippolito and Vindice discuss how Vindice will appear different and wonder about what they will be asked to do. Lussurioso speaks with melancholy Vindice about the law. He then employs him to kill Piato. He lies, saying that he was wholly virtuous and it was completely Piato who was behaving wrongly. In the end, Vindice and Hippolito discuss their new plan to dress the Duke's corpse in Piato's clothes and say that Piato killed him and then fled.
Act IV, Scene III
Ambitioso and Supervacuo see the Duchess and Spurio having their affair. Supervacuo goes to kill them then but Ambitioso holds him back saying that there will be a better time than now to get revenge.
Act IV, Scene IV
Vindice and Hippolito confront their mother about what she said to Piato, she denies it until Vindice reveals it was him. She tries to blame that he would be the only one who could convince her but eventually she repents. It rains and Hippolito and Vindice forgive her, saying she is free from that sin now. The brothers leave. Castiza enters and pretends to be promiscuous so as to punish her mother who says for her not to be and then they reconcile their differences and are happy again.
Act V, Scene I
Vindice and Hippolito speak about their plan next to the Duke's corpse and Vindice feels melancholy that he cannot reveal to Lussurioso now that he killed his father. Lussurioso enters and makes Vindice stab "Piato", then realises it is the Duke and falls for Vindice and Hippolito's plan. The nobles enter and one who tells the truth about the Duke and Piato being seen together is sentenced to death. The Lords say that Lussurioso is to become Duke and a feast is arranged. Vindice and Hippolito plan to seize the opportunity of the feast. Spurio is pleased is father is dead. Lussurioso says to audience that he will banish the Duchess. Ambitioso and Supervacuo plan to kill Spurio and then Ambitioso plans to kill Supervacuo.
Act V, Scene II
Vindice and Hippolito rally the Lords seen in Act I, Scene IV and they prepare to attack those at the masque.
Act V, Scene III
Lussurioso is seen as Duke and is acting tyrannically. He speaks of a 'blazing star' over them. Vindice's band of revengers enter and stab the four at the table (including Lussurioso). They exit. Ambitioso, Supervacuo, Spurio enter and find everyone dead. Supervacuo says he will be Duke and Ambitioso stabs him. Spurio stabs Ambitioso and a noble stabs Spurio. Vindice runs in with Lord Antonio and pretends he is in shock. The noble who is still alive is sentenced to death for murdering everyone. Lussurioso revives and Vindice reveals everything he did to him. Lussurioso dies. Lord Antonio is made Duke and Vindice reveals to him that he and Hippolito killed the Duke. They are sentenced to death. Hippolito is upset but Vindice is happy that all of his revenges went to plan. Antonio ends the play by saying that hopefully all of this death will cancel out the treason that has taken place and they can start a-fresh.