Medea, a witch and Colchian princess, helps the hero Jason get the golden fleece, a symbol of authority, from her father. In return, Jason brings Medea to his home in Thessaly to be his wife.

In Thessaly, Medea uses her magic to restore youth to Jason’s father Aeson. She makes a magic potion, puts Aeson to sleep and drains him of his blood, then refills his body with the potion.

Medea leaves Jason and flees to Pelias. His daughters want her to restore Pelias’ youth, so she begins the same spell that she used on Aeson. After Pelias goes to sleep, she has his daughters stab him to drain his blood, and they accidentally kill him. As he dies, he rises and says, “‘daughters, what are you doing? What has armed you / […] to kill your father?” (154). Medea then flees, kills Jason’s new bride, and later marries King Aegeus of Athens.