Agamemnon comes to his attendant with the errand – to take a letter to his wife Clytemnestra. The letter says that she and their daughter Iphigenia should not come to Aulis.
But Agamemnon tells the attendant sad truth. The seer has said that if Agamemnon wants the upcoming war against Troy be successful, he must sacrifice his daughter on the alter for gods. Agamemnon agreed with that at once, but upon some thinking has changed his mind, and now wants this letter to reach his wife as soon as possible.
The attendant takes the letter, but Agamemnon’s brother Menelaus intercepted it and is furious. He reproaches Agamemnon with treachery and says that he would find new friends and new commanders in this war.
The next scene informs that Clytemnestra and Iphigenia are already in the camp, and all the soldiers cheerfully meet them. It is known that Iphigenia has come to become the wife of Achilles, the bravest warrior in the army. Agamemnon has made this up to lure Clytemnestra and their daughter, but the letter which ordered them not to come, had never reached them, so they came at once.
Upon hearing that Clytemnestra and Iphigenia are already in the camp, Agamemnon started crying and swearing on his unfair fate. This picture melted Menelaus’s heart and he asked his brother for forgiveness, and told that he would not demand that Agamemnon sacrifice his daughter. Agamemnon is glad that Menelaus understood finally his father’s feelings, but he himself perfectly understands that he should sacrifice Iphigenia, or the army would rebel. He only asks Menelaus to keep Clytemnestra away and not let her see the sacrifice. Clytemnestra meanwhile is preparing everything for the future wedding.
Iphigenia is very happy to see her father after the long separation, but she feels that Agamemnon is sad. She asks him what the matter is, but he only smiles sadly and says that everything is good. When Iphigenia leaves, Agamemnon asks Clytemnestra to go back home, but she refuses and tells that she would be with her daughter by all the wedding ceremony. Agamemnon is miserable.
The next scenes dispose a random meeting of Clytemnestra and Achilles. Achilles comes to ask the king what they should do, as his warriors want to go to the war or go back home. During the conversation Clytemnestra finds out that Achilles knows nothing about the wedding. She is confused, but at that moment the attendant appears and tells her the awful truth, that her husband wants to kill their beautiful daughter. Clytemnestra asks Achilles for help, and he promises that will protect Iphigenia by the cost of his life.
Clytemnestra goes to her daughter and tells her everything. The young girl bursts in tears and, when her father enters, she kneels before him and beseeches not to kill her. Agamemnon tells her that it is not his whim, and all the warriors demand her death. Then cries outside are heard – the army is rebelling.
Iphigenia decides not to oppose the will of all the army and of her own free will enters the alter.
The last scene exposes how the attendant comes to Clytemnestra and tells her that her daughter was saved. The moment when the knife almost touched Iphigenia’s neck, everything around was obscured by the fog and then Iphigenia disappeared. Artemis saved valorous Iphigenia.
