After ten years of siege the Greeks have departed from Troy leaving behind a giant wooden horse as an offering to Pallas Athena. Only the prophetess Cassandra daughter of the Trojan king Priam wonders about the significance of their enemies disappearance. In a vision she has seen her dead brother Hectors ghost walking the ramparts. She has tried to warn her father of impending disaster and now urges her fiancé Coroebus to flee the city but neither man will listen to her. When Coroebus begs her to join the peace celebrations she tells him that she foresees death for both of them.
The Trojans offer thanks to the gods. Hectors widow Andromache brings her young son the heir to the throne before King Priam and Queen Hecuba. The warrior Aeneas arrives and reports that the priest Laocoön is dead. Suspecting the wooden horse to be some kind of a trick Laocoön had thrown his spear at it and urged the crowd to set fire to it when two giant sea serpents appeared and devoured him and his two sons. Priam and Aeneas order the horse to be brought into the city to beg pardon of Athena. Cassandra realizes that this will be the end of Troy.
Aeneas is visited by the ghost of Hector who tells him to escape the city. His destiny he says is to found a new empire that someday will rule the world. As the ghost disappears Aeneass friend Panthus runs in with news that the Greek soldiers who emerged from the horse are destroying the city. Aeneas rushes off to lead the defense.
The Trojan women pray for deliverance from the invaders. Cassandra prophesizes that Aeneas and some of the Trojans will escape to Italy to build a citya new Troy. Coroebus has fallen and Cassandra prepares for her own death. She asks the women if they will submit to rape and enslavement. When Greek soldiers enter the women collectively commit suicide. Aeneas and his men escape with the treasures of Troy.
Carthage North Africa. The people greet their queen Dido. In the seven years since they fled their native Tyre following the murder of Didos husband they have built a flourishing new kingdom. Didos sister Anna suggests that Carthage needs a king and assures her sister that she will love again. Visitors are announced who have narrowly escaped shipwreck in a recent stormthey are the remaining survivors of the Trojan army with Aeneas among them. Dido welcomes them. When news arrives that the Numidian ruler Iarbas is about to attack Carthage Aeneas identifies himself and offers to fight alongside the Carthaginians. Dido accepts and Aeneas rallies the united forces of Carthage and Troy entrusting his son Ascanius to the queens care.
Aeneas has returned victorious to Carthage. During a royal hunt he and Dido seek shelter from a storm in a cave. They discover their love for each other.
It is several months later. Narbal the queens adviser is worried that since Dido fell in love with Aeneas she has been neglecting her duties. He fears that in welcoming the Trojan strangers Carthage has invited its own doom. Dido enters with Aeneas and her court to watch an entertainment of singing and dancing. She asks Aeneas to tell her more about Troys last days. When he talks about Andromache Hectors widow who married Pyrrhus one of the enemy Dido sees a parallel to her own situation. Alone she and Aeneas again proclaim their love as the god Mercury reminds Aeneas of his duty and destinationItaly.
At night in the Trojan camp by the harbor a young sailor sings a homesick ballad. Panthus and the Trojan captains are worried about omens and apparitions that remind them of their failure to move on. Aeneas enters torn between his love for Dido and his duty to leave Carthage. He makes up his mind to see the queen one last time. But when the ghosts of Priam Hector Coroebus and Cassandra appear urging him to leave he orders his men to set sail before sunrise. Dido appears. Aeneas swears that he loves her but must leave her. She curses him. As dawn breaks the queen asks her sister to persuade Aeneas to stay but the Trojan ships are already on their way out to sea. Furious Dido orders a pyre built to burn his gifts and remembrances of their love. Now resolved to end her life she bids farewell to Carthage and everything she held dear.
The pyre has been set up. Priests pray for Dido who predicts that her fate will be remembered a future Carthaginian general Hannibal will avenge her against Italy one day. Then she stabs herself with Aeneass sword. Dying she has a vision of Carthage destroyed by eternal Rome. As the Roman Capitol is seen like a vision in the distance the Carthaginians curse Aeneas and his descendants.