Résumé: Diomedes offers Troilus's chariot horse as a gift to Cressida and renews his offer to care for her, but all she can bring herself to give him is a remnant of the veil she once offered to Troilus as a token of friendship.
For ten days Troilus fights the Achaeans on the battlefield and for ten nights he waits on the walls of Troy for Cressida's return. Meanwhile, Kalchas continually presses Cressida to forget Troilus and accept the protection of Diomedes.
On the tenth night Kalchas is away from his hut, informing the Achaean council that the sun god had told him that Troy will never fall if Troilus reaches twenty years of age. Cressida slips away from the hut in an attempt to reach Troy. Trying to find her way through camp, she runs into Diomedes, who renews his suit. Cressida gives in.
The tenth night passes. Troilus continues to fight by day and lament his loss by night. He dreams of Cressida kissing a great boar and consults his sister Kassandra, who used to interpret his dreams when they were young. Kassandra indicates that Cressida has yielded her sexual favors to an Achaean, but Troilus refuses to accept this.
In battle Troilus knocks off Diomedes's helmet and the remnant of Cressida's veil flutters out. Troilus recognizes it and realizes that Cressida hasn't been true to him.
Bitter, Troilus refuses any further help from Pandarus, who grudges the time spent trying to unite Troilus and Cressida.