 The action of the play begins with the Nurse explaining how Medea came to be in Corinth.  She wishes that Jason and his ship the Argo had never successfully completed the quest for the Golden Fleece, because then he never would have met Medea and set a horrific chain of events into motion.  The Nurse also gives the first glimpse of Medea's penchant for violence by revealing that Medea persuaded two royal daughters to kill their father in order for Jason to escape.

 Most recently, Jason has announced that he intends to leave Medea in order to marry the wealthy daughter of Creon, King of Corinth.  Medea is deeply hurt and angry, and cries out to the gods for revenge and justice while ignoring her children.  The Nurse is afraid that Medea is planning violent revenge against Jason and his lover.

 The Tutor arrives with the children and reveals that Creon plans to send Medea and her children away, and Jason is going along with the plan.  The Nurse is surprised by Jason's acquiescence, at which point the Tutor points out that people are inherently selfish.  The Nurse warns the children to stay away from Medea, since she will want to vent her anger at someone.

Medea curses and cries loudly, this time cursing her children as well as Jason. The Nurse speaks of how moderation in feelings and all things is best, while anger can bring ruin. The chorus arrives and desires to speak to Medea, who will not come outside to receive them.

The chorus also offers the viewpoint that men betray women all the time, so Medea should not be so hurt or surprised by Jason's actions. Medea prays loudly to the gods that Jason's life be destroyed. The chorus remarks several times upon the pain they hear in Medea's voice.

Medea leaves her house to visit with the chorus, saying that she has appeared primarily to keep up good relations between foreigners and locals. She comments on how badly women are treated in general, and asks the chorus to keep secret her plans of revenge against Jason and his new family. The chorus agrees. Creon arrives and tells Medea she must take her children into exile.

Medea begs Creon to allow her and her children to stay, but he refuses because he is afraid of her since she is a "witch". A fight ensues. Medea ends the fight by begging on her knees for one more day in the city, and Creon relents and allows her the twenty-four hours, promising that if she stays longer she and her children will be put to death.

The chorus sympathizes with how horrible things are for Medea, but she reveals that her begging was a strategy to win enough time for her revenge. Medea plots and rejects various methods of killing her enemies, finally settling on poison. She determines that she must wait until she has a place to flee to before she puts her plan into motion, and calls upon Hecate for assistance.

The chorus ends with a poetic ode describing how history must see that women are often wronged by men. They empathize with Medea and her abandoned, lonely life. Jason arrives on the scene and immediately chastises Medea for being too stubborn. He tells her she is lucky to be exiled rather than executed for her behavior.

Medea is glad to be able to vent her anger in person, and immediately launches into a lengthy list of things Jason has done to wrong her. Jason states that Medea never really did anything to help him, and should be grateful for all she has gained by coming to his homeland. He also says that he is looking out for everyone's best interests by marrying into money and power.

He speaks a bit about how women let emotion get in the way of logic, and tells Medea she should like his plan since it will benefit her. Medea calls him a fool, and a coward for doing everything behind her back without telling her first. Jason attempts to end the argument by insisting Medea take his money, but she refuses.

He warns her that she will regret her choice in the future, and leaves. The chorus comments on how excessive love can be dangerous, and the scene ends. Medea's friend Aegeus arrives on his way from a visit with the Delphi oracle. He reveals that he is looking for answers to get his wife to conceive children, but is going to a friend's house to interpret the oracle's prophecy.

Medea tells him what has happened to her, and begs him to allow her to make a new home in his lands. She promises him that she will be able to use her drugs and herbs to enable his wife to conceive if he does allow it. Medea manipulates Aegeus into swearing an oath on his honor that he will not change his mind once she does come to live with him.

Aegeus' only stipulation to Medea is that she must get to his kingdom on her own, so that he is not acting directly against another king's wishes. Aegeus swears his oath without realizing the crimes Medea intends to commit.

Once Aegeus leaves, Medea tells the chorus that she will kill Jason's bride by giving her an enchanted poisoned dress and crown that will kill her as soon as she puts them on. Medea also reveals that she will then kill her children, in order to hurt Jason more. The chorus begs Medea not to harm her children, but she insists that she must not be seen as weak.

Medea sends the Nurse to bring Jason to her. The chorus speaks an ode about the beauty and grace of natural love, and says Medea has fallen far from it. The chorus also says they doubt Medea will actually be able to bring herself to kill her own children once the moment arrives.

Jason comes in to listen to Medea. Medea apologizes and says she was an emotional fool, and begs for Jason's forgiveness. The children come out, and Medea puts their hands in Jason's, and is then overcome with tears.

She claims the tears are from imagining them reaching their hands out to heaven in the distant future. Jason is much more magnanimous in this scene now that he is getting his way, and forgives Medea her natural anger and upset at being cast aside for another woman. He tells Medea and the children he is making plans to take care of the children, and cannot understand why Medea is still so upset.

Medea promises to go into exile after the wedding, and asks Jason to intercede with Creon to allow the children to stay. She also asks Jason to ask his new bride (the princess) to intercede on the children's behalf. Finally, she gives Jason the enchanted dress and crown, claiming they were originally from her grandfather the sun god.

Jason does not want to take the gifts since they seem too valuable, but Medea convinces him that it will force his new bride to look favorably upon the children. Jason and the children leave with the crown and dress. The chorus speaks briefly about how painful life will be once this all plays out, and how little hope there is for the children or the bride.

The Tutor returns with the children and announces they can stay in Corinth, at which news Medea becomes more upset. The children and Tutor go back inside, and Medea has a long and searing monologue in which she debates whether to kill the children or not. By the end she hardens her resolve and decides again that killing the children is the path she must take.

The chorus speaks briefly about the pain of watching a child die. One of Jason's messengers comes in and tells Medea that the princess and Creon are dead. The messenger knows Medea is responsible, and urges her to flee. Medea demands to know whether the deaths were agonizing, and so the messenger tells the story of their deaths.

The princess, upon hearing Jason's request to let his children stay, is angry at first but then is swayed to compassion by Medea's gifts. Finding the gifts beautiful the princess puts them on nearly immediately and spends a little time admiring herself in the mirror. Very shortly thereafter, the poison begins to work and the princess begins to bleed from her head where the crown digs into it.

The poisoned dress causes her flesh to begin falling from her bones, and she dies in horrible screaming agony. Creon attempts to embrace his daughter and is himself exposed to the poison, dying in the same fashion as his child. The Messenger claims Medea has brought nothing but sorrow to herself, and leaves.

The chorus comments that Jason deserves what he gets, but that they feel sorry for the princess who did not earn this revenge. Medea tries one last time to justify her plans to the chorus, although her reasoning falls short of true logic. Medea leaves the scene going into the house to kill her children.

The chorus invokes the gods of earth and sun to stop Medea, and wonders at how she has become so cruel. The children's cries are heard from offstage, and the chorus debates helping them. Jason arrives and asks the chorus where he can find Medea. He is looking for his children to protect them from enemies that would hurt them because of Medea.

The chorus tells Jason that Medea has killed his children, and he responds with shock. Jason calls Medea a number of names and describes how much he loathes her. Medea appears above the stage in a chariot, carrying the bodies of her children.