The young Egyptian captain Radames loves the slave Aida. He does not know that she is the daughter of the Ethiopian king. Radames hopes to win the coming war against Ethiopia, so that he can free Aida from her slavery. Meanwhile, Amneris, daughter of the Egyptian king, harbors unrequited love for Radames. A messenger arrives to tell the priests and the king of an attack by the Ethiopians. In despair, Aida realizes that a victory for her beloved would mean poverty and desperation for her people.
The priests beseech the Gods for their help in the war with Ethiopia. Ramphis consecrates Radames as commander of the army.
Radames is victorious. Amneris awaits his return in the continued hope of winning his love. When news arrives of Radames’ purported death, she lures Aida into a trap. The slave girl confesses her love for Radames and Amneris declares her open rivalry for that love.
The Egyptians celebrate their victory over Ethiopia. Among the prisoners, Aida recognizes her father, Amonasro, who realizes that he should disguise the fact that he is the Ethiopian king. The king offers a prize to the victorious Radames and he asks for freedom for the prisoners. High priest Ramphis persuades the king to hold Aida and Amonasro as hostages. The king agrees to the marriage between Radames and Amneris and designates him as the future ruler of Egypt.
Amneris spends the night before her wedding in prayer with the high priest. Aida waits for Radames. Amonasro plans renewed war against Egypt and forces his daughter to worm Egypt’s battle plan out of Radames. Aida convinces Radames to flee in order to save their love. But along with the escape plan, Radames also gives away the battle plans to Amonasro, who is secretly eavesdropping. Amonasro unmasks himself as the king of Ethiopia. Radames realizes his betrayal and surrenders to the high priest and the Pharaoh’s daughter. Aida and Amonasro are able to flee.
Radames faces the tribunal of priests as a traitor to his country. Amneris promises Radames that she will plead for pardon if he will renounce Aida. But Radames refuses. The priests sentence him to death. Amneris regrets betraying her beloved.
Radames is buried alive in a sarcophagus. Aida is prepared to follow him unto death. In despair, Amneris begs for peace for her beloved.