At the beginning of the play, Medea's in dire straights. For one, her husband, Jason, has married another woman, Glauke, daughter of Creon the King of Corinth. On top of that, Creon banishes Medea and her two sons from Corinth. Medea, however, is not the kind of woman to take such mistreatment lying down. She swears bloody revenge and swiftly sets about finding a way to kill them all.
First, she convinces Creon to let her stay one more day in Corinth. It goes against his better judgment, but he allows it out of pity for Medea's two sons. This gives Medea enough time to put her plot into motion. Next Medea has to secure a safe place to retreat to once she's committed the murders. By an incredibly lucky coincidence, Aegeus, King of Athens, happens by. Medea promises to cure his sterility if he swears to give her safe harbor. Of course, she neglects to mention she's about to kill a bunch of people.
Now that Medea has the time and a safe place to retreat to, she can really get to work. She snookers Jason into believing that she's now cool with his new marriage. Medea begs her husband to ask Glauke if their two sons can stay in Corinth. Jason is moved and agrees. Medea gives Jason a gossamer gown and a golden crown to sweeten the deal for Glauke. Jason and the children trot off to the palace with hope in their hearts. Their hope is misplaced, however, for once again Medea neglects to mention a vital piece of information: the gifts are cursed.
A Messenger returns and tells Medea all about the horror she has wreaked. When the Princess put on the gown and crown, she received a rather nasty surprise. Her entire body caught fire and the flesh melted from her bones. When Creon saw his daughter's flaming corpse, he was so distraught that he threw his body onto hers and died as well. Medea thinks this is great. Now she only has one thing left to do, in order to leave Jason totally devastated – kill their sons.
The murder of her children isn't easy for Medea. She struggles with her motherly instincts, but in the end her revenge is more important. Medea drags the boys inside the house and kills them with a sword. Jason arrives too late to save his sons. Just as he's banging on the door to stop his wife, Medea erupts into the sky in a chariot drawn by dragons. Jason curses his wife, and she curses him back. He begs to have the children's bodies so that he can bury them. She refuses him even this, and takes their corpses away with her as she flies away triumphant.