Medea, like many tragic heroes and heroines, starts off with single minded determination. No matter what it takes, she's going to make Jason pay for taking another wife. Medea determines to kill the girl and her royal father Creon. There are also strong hints that Medea is plotting to kill her and Jason's two sons.
The only hitch in Medea's plan is that she needs a safe place to hide after she does murder. Incredibly conveniently, Aegeus, King of Athens, shows up. Medea promises to solve his sterility if he'll give her sanctuary. He agrees, and the stage is set for assassination.
Medea manipulates Jason into thinking that she's OK with his new marriage now. She begs him to convince his new wife to let her sons stay in Corinth. This is, of course, all a ploy to get a couple poisoned gifts into the hands of the unfortunate Princess. Jason offers a little resistance to taking the gifts, but not too much. Ultimately, the frustration stage isn't that frustrating for Medea.
Things get ugly. The Princess and Creon go up in flames as a result of Medea's cursed gifts. The description of their deaths is pretty nightmarish to say the least. Meanwhile, Medea goes through some emotional turmoil about killing her sons.
Medea commits the horrible act of infanticide, killing her two sons. Unlike most tragic figures, she suffers no repercussions for her actions. She flies away in her dragon-drawn chariot, without having to pay for her crimes. Jason tells her that she'll be haunted with guilt, but she seems to think she did the right thing. Euripides boldly defies traditional tragic structure by letting his heroine get away unscathed.