When Medea discovers that Jason has deserted her and married Glauce, the daughter of Creon, she vows a terrible vengeance. Her nurse, although she loves Medea, recognizes that a frightful threat now hangs over Corinth, for she knows that Medea will not let the insult pass without some dreadful revenge. She fears especially for Medea’s two sons, since the sorcerer includes her children in the hatred she now feels for their father.
Medea’s resentment increases still further when Creon, hearing of her vow, orders her and her children to be banished from Corinth. Slyly, with a plan already in mind, Medea persuades him to allow her just one day longer to prepare herself and her children for the journey. She already has decided the nature of her revenge; the one problem that remains is a place of refuge afterward.
Then Aegeus, the king of Athens and a longtime friend of Medea, appears in Corinth on his way home from a journey. Sympathetic with her because of Jason’s brutal desertion, he offers her a place of refuge from her enemies in his own kingdom. In this manner Medea assures herself of a refuge, even after Aegeus learns of the deeds she will soon commit in Corinth.
When the Corinthian women visit her, Medea tells them of her plan, but only after swearing them to absolute secrecy. At first she considers killing Jason, his princess, and Creon, and then fleeing with her own children. After she thinks about it, however, she feels that revenge will be sweeter with Jason living to suffer long afterward. Nothing is more painful than to grow old without a lover, without children, and without friends, and so Medea plans to kill the king, his daughter, and her own children.
She calls Jason to her and pretends that she forgives him for what he had done, recognizing at last the justice and foresight he had shown in marrying Glauce. She begs his forgiveness for her earlier rage, and asks that she be allowed to send her children with gifts for the new bride, as a sign of her repentance. Jason is completely deceived by her supposed change of heart, and expresses his pleasure at the belated wisdom she is showing.
Medea draws out a magnificent robe and a fillet of gold, presents of her grandfather, Helios, the sun god, but before she entrusts them to her children she smears them with a deadly drug. Shortly afterward, a messenger comes to Medea and tells her to flee. One part of her plan has succeeded. After Jason and the children leave, Glauce dresses herself in her wonderful robe and walks through the palace. As the warmth and moisture of her body come in contact with the drug, the fillet and gown cling to her body and sear her flesh. She tries frantically to tear them from her, but the garments only wrap more tightly around her, and she dies in a screaming agony of flames. When Creon rushes in and sees his daughter writhing on the floor, he attempts to lift her, but is himself contaminated by the poison. His death is as agonizing as hers had been.
Meanwhile. the children have returned to Medea. As she looks at them and feels their arms around her, she is torn between her love for them and her hatred of Jason, between her desire for revenge and the commands of her maternal instinct. The barbarous part of her nature—Medea being not a Greek, but a barbarian from Colchis—triumphs. After reveling in the messenger’s account of the deaths of Creon and his daughter, she enters her house with the children and bars the door. While the Corinthian women stand helplessly outside, they listen to the shrieks of the children as Medea kills them with a sword. Jason appears, frantically eager to take his children away lest they be killed by Creon’s followers for having brought the dreadful gifts. When he learns Medea had killed his children, he is almost insane with grief. As he hammers furiously on the barred doors of the house, Medea suddenly appears above, holding the bodies of her dead children, and drawn in a chariot that Helios, the sun god, had sent her. Jason alternately curses her and pleads with her for one last sight of his children as Medea taunts him with the loneliness and grief to which he is doomed. She tells him that her own sorrow will be great, but it is mitigated by the sweetness of her revenge.
The chariot, drawn by winged dragons, carries Medea first to the mountain of the goddess Hera. There she buries her children. Then she journeys to Athens, where she will spend the remainder of her days feeding on the gall and wormwood of her terrible grief and revenge.