In year 1250 B.C. during the late Bronze age, two emerging nations begin to clash. Paris, the Trojan prince, convinces Helen, Queen of Sparta, to leave her husband Menelaus, and sail with him back to Troy. After Menelaus finds out that his wife was taken by the Trojans, he asks his brother Agamemnom to help him get her back. Agamemnon sees this as an opportunity for power. So they set off with 1,000 ships holding 50,000 Greeks to Troy. With the help of Achilles, the Greeks are able to fight the never before defeated Trojans.
A battle between the armies of King Agamemnon of Mycenae and Triopas of Thessaly is averted when the great warrior, Achilles, defeats Thessaly’s champion in single combat, forcing Triopas and Thessaly to join Agamemnon’s loose alliance of all the Greek kingdoms. Meanwhile, Prince Hector of Troy and his younger brother Parisnegotiate a peace treaty with Menelaus, King of Sparta. However, Paris is having an affair with Menelaus’ wife, Queen Helen, and smuggles her aboard their home-bound vessel. Upon learning of this, Menelaus meets with Agamemnon, his elder brother, and asks him to help take Troy. Agamemnon agrees, as conquering Troy will give him control of the Aegean Sea. Agamemnon has Odysseus, King of Ithaca, persuade Achilles to join them. Achilles, who strongly dislikes Agamemnon, eventually decides to go, after his mother Thetis tells him that though he will die, he will be forever glorified.
In Troy, King Priam is dismayed when Hector and Paris introduce Helen, but welcomes her and decides to prepare for war. The Greeks eventually invade and take the Trojan beach, thanks largely to Achilles and his Myrmidons. Achilles has the temple of Apollo sacked, and claims Briseis — a priestess and the cousin of Paris and Hector — as a prisoner. He is angered when Agamemnon spitefully takes her from him, and decides that he will not aid Agamemnon in the siege.
The Trojan and Greek armies meet outside the walls of Troy; during a parley, Paris offers to duel Menelaus personally for Helen’s hand in exchange for the city being spared. Agamemnon, intending to take the city regardless of the outcome, accepts. Menelaus wounds Paris and almost kills him, but is himself killed by Hector. In the ensuing battle, Hector kills Ajax and many Greek soldiers fall to the Trojan defenses. On Odysseus’ insistence, Agamemnon gives the order to fall back. He gives Briseis to the Greek soldiers for their amusement, but Achilles saves her. Later that night, Briseis sneaks into Achilles’ quarters to kill him; instead, she falls for him and they become lovers. Achilles then resolves to leave Troy, much to the dismay of Patroclus, his cousin and protégé.
Despite Hector’s objections, Priam orders him to retake the Trojan beach and force the Greeks home; the attack unifies the Greeks and the Myrmidons enter the battle. Hector duels a man he believes to be Achilles and cuts his throat, only to discover it was actually Patroclus. Distraught, Hector euthanizes Patroclus and the armies agree to stop fighting for the day. Achilles is informed of his cousin’s death and vows revenge. Wary of Achilles, Hector shows his wife Andromache a secret tunnel beneath Troy; should he die and the city fall, he instructs her to take their child and any survivors out of the city to Mount Ida.
The next day, Achilles arrives outside Troy and challenges Hector; the two duel until Hector is killed, and Achilles drags his corpse back to the Trojan beach. Priam, in disguise, sneaks into the camp and implores Achilles to return Hector’s body for a proper funeral. Ashamed of his actions, Achilles agrees and allows Briseis to return to Troy with Priam, promising a twelve day truce so that Hector’s funeral rites may be held in peace. He also orders his men to return home without him.
Agamemnon declares that he will take Troy regardless of the cost. Concerned, Odysseus concocts a plan to infiltrate the city: he has the Greeks build a gigantic wooden horse as a peace offering and abandon the Trojan beach, hiding their ships in a nearby cove. Priam orders the horse be brought into the city. That night, Greeks hiding inside the horse emerge and open the city gates for the Greek army, commencing the Sack of Troy. While Andromache and Helen guide the Trojans to safety through the tunnel, Paris gives the Sword of Troy to Aeneas, instructing him to protect the Trojans and find them a new home. Agamemnon kills Priam and captures Briseis, who then kills Agamemnon. Achilles fights his way through the city and reunites with Briseis. Paris, seeking to avenge his brother, shoots an arrow through Achilles’ heel and then several into his body. Achilles bids farewell to Briseis, and watches her flee with Paris before dying.