Having arrived in Troy for the swap, Diomedes and Antenor are being escorted by Paris and Deiphobus, two sons of Priam, when they meet up with Aeneas. Aeneas and Diomedes recognize each other from the field of battle and exchange greetings of mutual respect, assuring one another that in the field of battle one would like nothing better than to vanquish the other and vice versa. Presently, Paris informs Aeneas of his commission: Aeneas is to go to Calchas’ house and fetch Cressida who is to swapped for Antenor. In a conversation aside, both Paris and Aeneas agree that persuading Troilus, who is currently lodged with Cressida, to relinquish Cressida won’t be an easy task. By and by, Aeneas goes to fulfill his commission. Meanwhile, Paris asks Diomedes who he--Diomedes--thinks is the more deserving of Helen he--Paris--or Menelaus. Diomedes replies that both deserve her equally as both are compromising their honor in coveting a compromised woman to which Paris ripostes that Diomedes is like a buyer who would disparage a merchandise that he intends to buy (so he can bargain for a lower price), while Paris, who has no intention of selling, won’t advertise Helen’s worth.
As they are about to go their separate ways, both Troilus and Cressida lament that the night had been too brief when they are interrupted by Pandarus and then by a knocking at the door. Pandarus, who has been mocking the pair for their lovemaking to Cressida’s chagrin, goes to answer the door while Cressida has Troilus hide in her room. (It’s Cressida’s wish to keep their affair a secret.) At the door, Aeneas greets Pandarus and asks to see Troilus. Pandarus denies that Troilus is there--to no avail. Aeneas insists that Troilus is there, and anon Troilus himself comes out from hiding. Troilus is told of what Priam and his counselors have determined: Cressida will go to her father in the Greek camp in return for Antenor. Cursing his fate, Troilus asks Aeneas to deny that they had met at Cressida’s lodging, that if he is asked if he had met Troilus at Cressida's lodging that Aeneas should say 'no' that they had met by chance. Aeneas agrees to do as Troilus asks and presently they go to meet Paris, Deiphobus, Diomedes, and Antenor.
When told that she is to go to her father in the Greek camp in return for Antenor, Cressida objects, arguing that she has no ties with her father now, that the only man she now cares for is Troilus. Pandarus argues that she has no choice on the matter, that she must go as Priam has decreed. Cressida laments her fate, while Pandarus laments for Troilus.
Resigned to his fate, Troilus directs Aeneas, Paris, Deiphobus, Diomedes, and Antenor to Cressida’s lodgings. There Troilus’ himself will persuade Cressida to submit her will to Priam’s decree.
To no avail Pandarus tries to calm down Cressida when Troilus appears. Troilus and Cressida embrace, and anon Troilus breaks the bad news. He tells her, however, that as long as she remains true that he will visit her in the Greek camp. Cressida wonders how Troilus could question her faith. But led to understand that he means it in the best possible sense, Cressida dissuades Troilus from attempting to visit her in the Greek camp what with the danger he’ll put himself in. Troilus assures Cressida that by bribing the Greeks sentinels the danger will be mitigated. He tells her, however, that she must be on her guard as the Greeks excel in the arts of singing, dancing, and wooing all of which upsets Cressida and prompts her, in turn, to question Troilus’ faith and loyalty. While Troilus and Cressida are thus engaged, Aeneas and Paris repeatedly call out to Troilus to hurry.
Eventually Troilus beckons the party in. The principles of the exchange are identified and when Diomedes praises Cressida’s beauty, Troilus grows angry. The praise is uncalled for, as far as Troilus is concerned, as only thing that Troilus would have Diomedes do with respect to Cressida, as she is understood to be Troilus’ dearest, is to treat her fairly. Presently, they repair to the gate where Troilus will finalize the exchange by relinquishing Cressida to Diomedes.
Meanwhile, the sound of a trumpet, signifying the imminent engagement of Hector with a Greek on their one-on-one battle, prompt Paris and Deiphobus to hurry to the field where Hector is expecting them to be his attendants. They blame Troilus’ for taking so much time with Cressida for their present tardiness.
Urged on by Agamemnon, Ajax sounds his trumpet but to no avail: Hector does not respond. Achilles attributes it to the time of day as it’s still very early. Anon, they espy Diomedes with Calchas’ daughter in the distant. When Diomedes arrives, he introduces Cressida to the Greeks who each extend their gracious welcome with a kiss. As a sort of joke, on account of Menelaus’ cuckold status, the Greeks and Cressida conspire to deprive Menelaus from participating in the kissing part of the welcome. The greetings at an end, Diomedes escorts Cressida to her father.
Anon, the trumpet sounds, signifying Hector’s approach. Aeneas steps forth to negotiate the terms of the fight. As Hector and Ajax are cousins (Ajax’s mother is Priam’s sister), and as Hector is especially loath to kill his own blood relation, it‘s decided that the fight will be decided by points accumulated in terms of hits. As the fight begins, Agamemnon takes notes of a melancholy Troilus. Ulysses informs him that though Troilus is the youngest of Priam’s sons that Troy would still be well spoken for if Hector fell and Troilus stood in Hector’s stead. By and by, the fight ends in a draw.
Based on mutual respect, the opposing sides agree to partake in a feast at the Greek camp. There Hector makes acquaintance of Agamemnon, old Nestor and Achilles. Achilles boasts that he will slay Hector and vice versa. Meanwhile, eager to find Cressida, Troilus asks Ulysses as to her whereabouts.