It is 480 BC and the elderly Persian council members gather outside the palace in Susa. The councilmen, along with the King's mother, are waiting to hear news from the war. Persia is fighting the Greek army, and they are fighting specifically to avenge the Greek victory over their forces more than ten years previously. The council members praise their king, Xerxes, whom they believe to be mighty and all conquering. However, although they believe the Persian army is strong and powerful, they are also worried about the war's outcome.
Atossa, Xerxes' mother, shares their fears. She calls upon the Gods, and her late husband King Darius, to help her son defeat the Greeks, but she has nightmarish visions of a battle that the Persians can never win, and feels a sense of foreboding that she cannot explain. As she is speaking, a messenger approaches her and tells her that the Greeks have again vanquished the entire Persian army. The messenger says that he observed the many dead himself, and that the worst of it occurred at Salamis, where the Persian fleet was routed by the Greek navy. Mounted soldier also fell in their thousands to the Greek army.
Atossa is grief stricken but unable to express the depths of her grief in mere words. She asks of her son, and is told he is still alive, but he reels off a list of names of the great Persian warriors who have been killed in the fighting. He also informs her that the Persian survivors ran in every direction and he does not know the specific whereabouts of any of them.
Atossa says that her foreboding dreams have come true. She expresses hope for a better future and begs the Gods to protect the empire and the soldiers who are left. She is then visited by the ghost of her husband Darius, offering him libations, and offering gifts to the gods as well. Darius asks what has happened to cause such woe and after listening says that his son acted in haste. Xerses has believed himself more powerful than the gods and his arrogance has caused the greatness that was achieved by the rulers who went before him to be lost. Darius' ghost orders the Persians to stop warring with the Greeks.
Xerxes arrives with a few of his men, lamenting his ruin, and the ruin of Persia. All of Persia's heroes are dead. The chorus ends the play by lamenting the misfortune of the Persians.