At the start of the play, Medea is a mess. Her husband, Jason, has married King Creon's royal daughter. Medea's slaves, the Nurse and the Tutor, worry about what terrible things their mistress might do in retaliation.
Creon shows up and tells Medea that she and her two sons are banished. Medea's been talking too much trash about the marriage, and the King is afraid she might do something drastic, like kill everybody. Our heroine pulls on Creon's heartstrings and convinces him to let her stay one more day. As soon as the King is out of earshot, Medea swears to murder him and his daughter.
Medea tricks Aegeus, King of Athens, into offering her sanctuary. Now she has somewhere to run after she does her killings. She manipulates Jason and her sons into taking the Princess some cursed gifts. As a result, both Creon and his daughter are burned alive by magic flame.
After savoring all the gory details of the royal family's incineration, Medea proceeds to the final, and most painful, step in her plan. In order to wound Jason as deeply as she possibly can, she takes their two sons inside and kills them with a sword.
Jason shows up too late to save his sons. He batters on the door of the house trying to get inside. Before he can get in, Medea erupts into the sky in her private dragon chariot. She mocks Jason from the sky with her two boys' corpses beside her.
Medea and Jason have their last bitter shouting match. They both blame each other for what has happened. Jason begs to bury his sons or at least to touch them one last time. Medea refuses.
Medea flies ways in her dragon drawn chariot. Her revenge is complete. Her husband is emotionally destroyed.