Hieronimo begins building the stage for the play. The Duke of Castile walks by and asks him why he is building the stage by himself (literally, he asks where are his helpers). Hieronimo replies that it is important for the author of a play to ensure all aspects of its performance run smoothly. Hieronimo then asks Castile to give the king a copy of the play and to throw a key onto the floor for him when the audience has been seated. Castile consents and leaves. Balthazar comes along, with his beard half-on and half in his hand. Hieronimo scolds him for being unprepared. Then, along again, Hieronimo reminds himself of the reasons for his revenge: the death of his son and the recent suicide of his wife. He again resolves aloud to get revenge.
The time has arrived for the wedding festivities. The King, the Viceroy, the Duke of Castile, and their entourage sit down in front of the stage. The King hands the Viceroy the night's program, which summarizes the play's plot. Then, the play begins.
In the text of The Spanish Tragedy, a note is included to any readers (or perhaps audience members) explaining that the play was transcribed in English for the benefit of the general public; so the characters are comprehensible to English-speakers, despite Hieronimo's instructions to the contrary. Balthazar opens the production by entering—along with Hieronimo and Bel- Imperia—and giving a speech in the character of Soliman (the Turkish emperor), describing his pleasure at the conquest of Rhodes and his love for the beautiful Perseda. The king praises Balthazar's acting, and both the Viceroy and Castile note that he draws on his real-life love for Bel-Imperia. Hieronimo and Bel-Imperia, meanwhile, act the parts of the bashaw and Perseda. Soliman professes his affection for his friend Erasto, but when Lorenzo enters in the part of the knight Erasto, Erasto and Perseda exchange professions of love to Soliman's dismay. Hieronimo then persuades Soliman to have Erasto killed, against Soliman's initial reluctance to kill a friend. He then stabs Erasto. When Soliman tells the grieving Perseda that she can have his love to replace the loss of Erasto, she angrily rejects him, stabs him, and then stabs herself.
The watching nobles are all extremely impressed by the play. The King congratulates Hieronimo, and the Viceroy remarks that Bel-Imperia would have treated his son better had the play been reality. But then Hieronimo goes on to provide his promised conclusion, revealing that the murders that were just enacted were in fact committed, the stabbings were real, and all the other actors are now, in fact, dead. Hieronimo graphically provides the reason for his revenge by revealing his dead son's body from behind a curtain where it has been hidden. He describes the cruel murder of his own son and then directly addresses the Viceroy whose own son Hieronimo has just killed, telling the Portuguese ruler that he understands his grief, having felt it himself. He reveals that he constructed the play specifically as a device of revenging himself on the murderers of his son and also notes that he rewrote Bel-Imperia's part so that she would not have to die at the end but that she decided to take her life anyways, out of despair for the loss of Horatio.
Hieronimo then runs off to hang himself, but the King, Viceroy and Castile, now enraged and confused by the sudden disaster, manage to find him and stop him. Hieronimo curses them, as they angrily demand his reasons for killing the Viceroy's son and Castile's children. Hieronimo repeats the fact (previously explained) that Lorenzo and Balthazar killed his son. The Viceroy realizes that Bel-Imperia must have been Hieronimo's accomplice, since she stabbed Balthazar. The king then berates Hieronimo for not speaking (even though he has already told the king everything he needs to know), at which point Hieronimo vows silence, perhaps intending to never reveal (though the Viceroy has already guessed it) the fact that Bel-Imperia helped him. He then bites out his tongue. The King, Viceroy and Castile are disgusted as the tongue plops to the floor. They then insist that Hieronimo write down his confession (though he has already spoken it), and Hieronimo then asks, using signs, for a knife with which to sharpen his pen. They provide him with one, allowing Hieronimo to immediately stab the Duke and then himself. The king, surrounded by the bodies of the dead, realizes and laments the fact that the heirs to the Spanish monarchy have been destroyed. The Viceroy echoes his grief, voicing a desire to sail across the world weeping for his dead son.
This scene is both ingenious and problematic. The ingeniousness lies in the way Kyd constructs the ironic deaths of Balthazar and Lorenzo. Believing that they are acting out a play to celebrate a wedding—a new beginning to life—they in fact act out their own, very real deaths. In a piece of grim wordplay, the "plot" Hieronimo spoke of in IV.i becomes the plot of the play. And the plot results in Hieronimo's long-awaited revenge.
The central irony of the act, however, is that even in revenge, Hieronimo does not find relief from his pain. First of all, Bel-Imperia is dead, needlessly, by her own hand, overcome by grief. And the murder of his son's murderers does not even relieve Hieronimo's grief. When Hieronimo agonized over how his grief felt oppressive and inescapable in the opening lines of Act III, scene vii, revenge was then held out as a possible relief. Instead, Hieronimo finds only more grief after the death. "Here lay my hope," says Hieronimo, and the repetition of the words "Here lay" at the beginning of his next four lines (an example of anaphora), echoes the words "Here lies ", the introduction to many epitaph inscription. And Hieronimo does recite an epitaph, both for himself and his son. The two deaths are in fact linked as the same death. Those who murdered Horatio "murdered me", says Hieronimo, and the corpse that lies on the stage is not only Horatio's corpse but also the corpse of Hieronimo's "hope" his "heart", his "treasure", his "bliss." In short, it is his own corpse, the corpse of everything he found valuable in life. And as the long description of Horatio's murder and his plot for revenge makes clear, there is no joy attached to the act. Hieronimo only wishes for silence: "I have no more to say" are his final words before running off and attempting to hang himself, to silence himself forever.
And Hieronimo is conscious of the new grief he has created on top of the old. "Speak Portuguese," he demands, "whose loss resembles mine: / If thou canst weep upon thy Balthazar, / 'Tis like I wailed for my Horatio." Hieronimo still uses the language of justice to describe his act: night covers "accursed crimes," the murderers were "traitors," he took a "vow" to revenge Horatio when he dipped the bloody handkerchief in his wounds, a handkerchief that now makes its final appearance. But this consciousness of the suffering in others, and its similarity to his own pain, demonstrates that Hieronimo still has empathy for others. Indeed he seems to feel the pain of others as well.
In classic Greek tragedy, there was often a defining moment in a play where the tragic hero would realize his folly, his fatal error or hamartia. This moment was called the hero's anagnoresis. Tragedies do not need such a moment to be tragic (Shakespeare's plays often didn't possess such a moment), and Hieronimo does not seem to have a moment of self-recognition here. He doesn't consciously renounce revenge or reflect on the futility of replacing death with death. But Kyd has created a very poignant image of that futility in this scene, and if Hieronimo cannot realize it, then the audience can. At this moment, Hieronimo is the closest he has come to being a true tragic protagonist, destroyed by evil forces beyond his control yet still recognizably human. It is a terrible moment but also a profound one.
In the rest of the scene, though, it seems that Kyd loses control of his play. Hieronimo's speech already pushes the edges of sensationalism, and his biting out of his tongue only makes the action more sensational. It is a fairly obvious symbol of his already stated desire to be silent, to have no more words. It must, of course, be theatrically effective; but it also paints Hieronimo as completely insane. And when Hieronimo stabs the Duke of Castile, we are much more likely to feel pity for Castile and his friends than we are for Hieronimo. Castile was innocent of any crime and actually spoke highly of Hieronimo in III.xiv. In short, this scene wipes out Hieronimo's ambiguity (the conflict between a good man driven to Machiavellian means and a murderer who understands the grief his victims feel) and replaces it with lunacy.
The scene does heighten the ambiguity and tension that have existed in the entire play, between the "play" world and the real world. This tension is related to the double perspective in which the play encourages us to view Hieronimo. If we watched the Soliman and Perseda playlet within IV.iv as a member of an audience, we would be a viewer watching two viewers (Revenge and Andrea, who, remember, never leave the stage) watching several other viewers (the assembled nobles) watching a play. Several levels of reality separate us from the world of Soliman and Perseda, and on one level we are very isolated from this action. But if we look into the world of The Spanish Tragedy, we see an exact mirror of ourselves—spectators in the middle of watching a tragic play. This increases the viewer's sense of identification with the world of the play, as does the sudden collapse of the distinction, of the real world and the world of Soliman and Perseda. The murders are real, the actors are really dead, and so the boundaries between real world and play world are revealed to be, from one perspective, unbreakable, but fluid, and collapsible when we look at it another way.