The scene: ancient Egypt, near the royal palace at Memphis.

As Egypt plans to defend the Nile valley from Ethiopia, Radames, a young Egyptian captain, dreams of leading his army to victory. He is in love with the Ethiopian slave, Aida, and hopes to win her freedom. Aida returns his love and cheers when Radames is appointed commander. She feels tremendous conflict, however, in loving Radames while he goes to war against her father, Amonasro, the king of Ethiopia. Aida is the slave of the Egyptian princess Amneris, who also loves Radames. Amneris tricks Aida into revealing her love and then declares that she, Amneris, will win Radames.

When Radames returns triumphant, Amonasro is hidden among the prisoners. Although Aida recognizes him, Amonasro announces that the king of Ethiopia is dead and pleads for his fellow prisoners’ lives. Moved, Radames asks for their release as his reward for victory. The king grants his request, freeing all but Amonasro, and bestows on Radames Amneris’ hand in marriage.

The night before the wedding, Aida waits for Radames outside the temple. Her father approaches, demanding that she learn from Radames the Egyptians’ battle route into Ethiopia. She refuses but he forces her to agree, calling upon her loyalty to her country. Amonasro hides. When Radames arrives, he tells Aida he will ask his king to marry them when he returns from battle. Aida instead asks him to run away to Ethiopia with her, causing Radames to reveal the Egyptians’ route. Both Amonasro and Amneris have been listening, and while Aida and her father escape, Radames admits to treason and surrenders.

Amneris offers Radames a chance to save himself by renouncing Aida, but he refuses. Rebuffed, she curses him and then the priests when they sentence him to be buried alive. Locked in the crypt, Radames discovers that Aida has chosen to join him in death. The lovers bid farewell to life, as a penitent Amneris prays for peace in the temple above.