地牢裡暗無天日，拉達梅斯思念起阿伊達，但不知她目前下落如何。忽然他感覺到他不是獨自一人在地牢中， 原來是阿伊達在先前已經悄悄潛入，只為等待在愛人懷裡相擁而終。在甜蜜的二重唱裡，命運之神取走了這對戀人的生命，卻留給他們永恆的愛情。
─ 劇終 ─
ACT I
Scene One
In Memphis, during Pharaohs' age.
In the royal palace of Memphis, the Great Priest Ramfis is questioning the gods to choose a guide for the egyptian army, having to fight against the Ethiopian invasion that is menacing Thebes.
The oracle indicates Radamès, a young warrior who is proud of this honor, because he secretly loves Aida, an Ethiopian slave, and wants to show his bravery.
But Radamès is loved by Amneris, the daughter of the Pharaoh. She realizes Radamès' secret love for the slave, and simulating to be friendly she plots vengeance.
When the Pharaoh arrives and announces that Radamès will guide the Egyptian army, Aida is astonished: she is the daughter of the Ethiopian King, Amonasro, who his lover Radamès is going to kill.
Scene Two
In the Temple of Vulcano, a great ceremony is given to honor Radamès.
He is given the sacred sword and is blessed by the Great Priest, Ramfis.
ACT II
Scene One
In Amneris' rooms.
Amneris tells Aida that Radamès has died, to make her discover her feelings.
Aida falls into despair, and Amneris reveals that Radamès is alive and that she too is fond of him. Amneris goes away, declaring again that her vengeance will fall upon Aida.
Scene Two
Near a city gate of Thebes.
Radamès is returning after his triumph with his troops: Amneris crowns him as the winner.
Among the prisoners he has taken with him there is Amonasro, who tells Aida not to reveal he is the King of the Ethiopians.
The Priests suggest to keep only Amonasro and to free the other prisoners: the Pharaoh accepts. Afterwards, the Pharaoh gives her daughter Amneris as spouse to Radamès. Radamès and Aida are desperate, but they try to conceal their feelings.
ACT III
On river Nile's banks.
The royal marriage is near, and Amonasro persuades Aida to use her influence on Radamès to know the way to reach the Ethiopian army.
Later, the lovers meet, and plotting their escape from Amneris, Radamès reveals her that Napata Pass is unguarded. Amonasro comes out from the dark and declares that he will use Napata with his army. Radamès realizes the treason and angrily jumps over Amonasro, but Amneris and the Great Priest arrive in the same moment. Amonasro goes against Amneris, but Radamès protects her. Then he admits to have revealed the important information to the Ethiopians and is imprisoned by the Priests.
ACT IV
Scene One
In the Pharaoh's Palace.
Amneris, still loving Radamès, goes into the prison and tries to persuade him to renounce to Aida. If he does so, she will obtain his freedom from the Pharaoh.
But he refuses, and declaring his love for Aida he chooses to be judged.
The Priests' Court sentences him to death: he will be buried alive.
Scene Two
In the Temple of Vulcano.
Under the Temple ther is the crypt where Radamès will have to die. After the crypt is sealed, Radamès realizes that Aida is there, to die with him.
While Amneris, in the Temple, is desperately crying, Aida and Radamès wait toghether to die, singing their last hymn to love and their farewell to earth.
