Thersites enters with a letter for Achilles. While Achilles reads the missive, Patroclus tries to engage Thersites in banter, only to find the misanthrope even more spiteful than usual towards him (on account of his status as Achilles' "masculine whore"). Achilles, having finished the letter, announces that it is from Queen Hecuba, charging him to fulfill an oath he made to marry the Queen's daughter, Polyxena. Achilles then turns his attention to the feast at hand, which he is holding in his tent. Thersites, alone on the stage, unleashes his usual venomous gall, foremost upon Menelaus.
The Trojans, having imbibed hardily, are escorted from Achilles' tent and back to their city. Meanwhile, as per his promise, Ulysses and Troilus slip away to Calchas' tent, where Diomedes is already heading. Thersites, overhearing Troilus' plan to see his beloved, declares that Cressida is as much a false-hearted "drab" as anyone. He determines to follow after and see the lechery unfold.
At Calchas' tent, Cressida and Diomedes meet while Ulysses, Troilus and Thersites watch. It quickly becomes apparent that there is predetermined business between Diomedes and Cressida. Diomedes desires Cressida to spend the night with him, and though Cressida is not immediately encouraging in that respect, she nevertheless fails to dissuade his affections. Troilus cannot believe his eyes and ears; Ulysses, alarmed that Troilus' grief and rage will betray his presence in the Greek camp, reminds Troilus that he promised not to speak, only to watch. Cressida's flirtatiousness continues; she even gives Diomedes the sleeve that Troilus had given her. In a moment of repentance she snatches it back from him, but then Diomedes takes it from her. He swears that he will wear the sleeve on his helm the following day at battle so that her Trojan lover will be incensed to challenge him. Upon parting, Cressida promises to see him later that night.
To call Troilus devastated is an understatement of his grief. When Cressida goes back into Calchas' house, Troilus declares that he did not see her just now. In an intense display of denial, he separates "Diomed's Cressida" from his own. Troilus thus saves his own love for Cressida while declaring with rancor his hatred for Diomedes, whom he announces he will meet the next day in battle. Aeneas interrupts Troilus to tell him that Hector is already arming himself for the next day's battle. Troilus returns to Troy, and Thersites gets the last word in the scene: "Lechery, lechery, still wars and lechery."
Back in Troy, Andromache and Cassandra both attempt to dissuade Hector from taking the field. Andromache has had foreboding dreams, and Cassandra foresees Hector's death. Hector refuses to listen to them, insisting that his honor binds him to take the field. However, when Troilus shows up with blood boiling, Hector tries to talk his younger brother out of suiting up for battle. Troilus defies his brother's advice, just as Hector defies Andromache, Cassandra, and later Priam. As they prepare for the field Pandarus enters with a letter from Cressida, which Troilus scornfully sets aside.
We are then presented with several tableaux from the day's battle. Thersites watches, brimming with cynicism, as Troilus and Diomedes skirmish, until Hector interrupts his voyeurism and Thersites shows his cowardice. Diomedes claims to have bested Troilus in the field and tells his servant to relay this news to Cressida. Meanwhile Agamemnon enters to say that the Trojans are rallying; Nestor comes with a testament to this news, leading a throng of soldiers carrying Patroclus' slain body. He orders the soldiers to bring Patroclus' body to Achilles, to spur him into battle, and also to spur Ajax onto the field.
Ajax enters, and he and Diomedes call for Troilus. Although outnumbered two to one, Troilus does well against the warriors. Meanwhile, inspired by his rage over the death of Patroclus, Achilles goes after Hector. Hector, for his part, sees a Greek with armor that he wants for his own; he chases the Greek offstage. Achilles gathers his troops, the Myrmidons, and declares that they should encircle Hector and slaughter him. Hector reenters with the nifty-armored Greek, now slain, and the Myrmidons jump him. He declares that he is unarmed, which doesn't bother Achilles or his men; they slaughter him nonetheless. Achilles orders the Myrmidons to declare that Achilles alone killed Hector; he decides to drag the slain Trojan through the battlefield behind his horse.
News of Hector's death reaches both the Trojans and the Greeks. Upon hearing about it, Troilus first despairs, then resolves himself to fight the Greeks as brutally as he can and swears to take revenge on the "great-sized coward," Achilles, who slew his brother. Pandarus interrupts this vow, and Troilus dismisses him with a curse. Pandarus remains on stage to deliver the play's final thoughts. He is plagued by symptoms of syphilis, which he alludes to in what must be Shakespeare's most cynical final address to an audience. Pandarus bemoans his fate and the poor reputation of his trade, ever-so-subtly addressing the audience. Thus, with the pathetic diatribe of a diseased man, Shakespeare's play tapers to a close.
There is much to discuss with regards to this final act, and none of it is pleasant. The ending is quite eerie, and contributes as much as anything to the widespread feeling that Troilus and Cressida is a pessimistic - even nihilistic - play. The action of the final scenes does not close the play in a definitive fashion, in the manner of the endings of the majority of Shakespeare's tragedies. Compare the relatively tangential action of this play with the ending of Romeo and Juliet, for instance. That play is also about tragic lovers, and ends with the culmination of their tragedy. This play, in contrast, ends with the death of Hector - an important figure, but hardly the hero of the play.
The reason for this off-center ending may have to do with the odd nature of this drama: it is a play about Troilus and Cressida, but even more it is a play about questions of meaning. The real drama of Troilus and Cressida's own relationship, in their few scenes together, rests in their negotiation of what it means to be in love, what it means to desire, what it means to vow - or to break a vow. Cressida's betrayal of Troilus, then, is a betrayal not merely of a single man, but of the idea of meaning itself. When she turns on her lover, honor dies. Thus, the death of honor - and who in this play is honorable if not Hector, the veritable embodiment of fair play - is, on a higher level, quite fitting.
Likewise, the play's limp, grotesque ending, where Pandarus comes out and delivers an abstruse message about pitying one's local whoremaster, is the culmination of the play's cynical emptiness. Pandarus ultimately replaces Hector as the play's mascot, so to speak. Hector's values - honorable, valiant action on the battlefield and prudence off of it - fade and Pandarus' - equivocal glad-handing and, well, pandering - predominate. Indeed, Shakespeare suggests that those who put on plays, "Brethren and sisters of the hold-door trade," are much like Pandars: sweet-speaking, people-pleasing go-betweens in a fiction. The end of the play, then, resembles to some extent the end of a visit to a Jacobean whorehouse. The fun is over, the sweet promises are broken, and nothing but hollow guilt, disease, and emptiness remains.
Although there is a general tendency to condemn Cressida, we must not be too quick to do so. In her day, Cressida represented the alleged deceitfulness of all womankind; and to some degree Shakespeare's view of Cressida conforms to the legend. She capsizes under Diomedes' pressure to have sex with him (and Diomedes' pressure isn't much; he seems quite willing to let her alone), and her last words in the play - "Ah, poor our sex! This fault in us I find, / The error of our eye directs our mind" - are damningly misogynistic. But, as we've seen again and again, this is a philosophical play. It's about characters, yes, but more than that it's about questions of meaning and language.
Cressida's quick transformation from loving woman to deceptive betrayer seems to speak to certain elements of Shakespeare's culture. Troilus' declaration that "This is Diomed's Cressid" is, in this light, correct. "Cressida," as a cultural word synonymous with "false woman," is one character; "Cressida," the witty and guarded woman we saw in the first acts of the play, is another. Troilus' moment of denial thus becomes one of the play's major points: Cressida the woman is transformed into Cressid the false: a misogynistic representative of all women.
Of course this is just one way to read the play. There is no getting around the difficulties of Cressida's character in the scene with Diomedes. As in the kissing scene, the meaning varies from performance to performance. This flexibility of meaning - meaning as contingent upon performance - is essential to the play as a whole. Cressida may be a victim in a male-dominated society; she may simply be false - the only sure thing is that she, as a character and as a woman, is open to interpretation. It is in this process of interpretation that Troilus and Cressida gains its life and its resonance.