For seven years the Greeks and Trojans have been at war following the Trojan prince Paris' abduction of Helen, the most beautiful woman in the world, from her Greek husband Menelaus.
The Greek army is encamped under the walls of Troy and, when the play begins, the war has reached stalemate. The Greeks are quarrelling amongst themselves. Achilles, their greatest champion, refuses to fight and has withdrawn to his tent with his lover, Patroclus.
Ulysses tries to get Achilles back to fighting by making him jealous of a rival warrior, Ajax. Ulysses announces Ajax as a new hero who will meet Hector, the Trojan champion, in single combat.
The Trojans are debating whether they should continue the war, just to keep Helen, or return her to the Greeks. Hector says that she is not worth the lives she costs, but when his brother Troilus suggests that honour demands they continue to fight for her, Hector agrees with him.
The single combat takes place between Ajax and Hector and ends in a show of friendship, but hostilities are resumed the following day.
Troilus is distracted from military concerns by his love for Cressida. She is the daughter of Calchas, a Trojan who has defected to the Greek camp whilst leaving Cressida in Troy.
The young lovers are eagerly assisted by Cressida's uncle Pandarus, who acts as their go-between. After just one night together the lovers are separated – Cressida is sent to join her father in the Greek camp, in exchange for the captured general Antenor.
Cressida almost immediately betrays Troilus by agreeing to become the Greek Diomedes’ lover. Troilus finds out and is plunged into despair.
Stop reading now if you don't want to know how it ends...
Hector goes into battle, despite his sister Cassandra's prophecies of doom. Achilles learns of the death of Patroclus and this makes him want to fight again. He can’t defeat Hector in single combat, but catches him unarmed and kills him. Achilles drags Hector's body around the walls of Troy.
The fall of Troy is now certain and the angry and heartbroken Troilus takes over from Hector as the Trojan champion, vowing revenge on Achilles. The dying, disease-ridden Pandarus is left to end the play.