All’s fair in love and war, though not every stratagem proves successful. This is a bitter lesson that the sorceress Medea is forced to learn. When Athens appears to be in danger of losing a war, King Egeo summons the aid of the powerful Medea. As a reward, he offers her the prospect of becoming his queen. The young hero Teseo is also fighting for Athens and is secretly bound by love to Princess Agilea, a ward of Egeo. Equally secretly, Medea also loves Teseo, but he does not return her affection. Once the war is won, thanks to Medea’s help and Teseo’s bravery, Egeo suddenly rejects the lowborn sorceress and wishes to marry Agilea instead. The princess is none too pleased about this because Teseo is the only man for her. Medea, on the other hand, is offered one of Egeo’s sons in marriage. This son has so far lived far away from court and not even his father knows what he looks like. Medea is not terribly disappointed at this, since she now hopes that the unknown son will never turn up, leaving her to marry Teseo once her rival has conveniently become Egeo’s wife. However, Teseo and Agilea refuse to be parted and are determined to resist all other plans. But when Medea brings her wicked spells into play and subjects Agilea to horrific agonies she succeeds in persuading the princess to forsake Teseo. Agilea now pretends to love Egeo. But Teseo soon sees through Agilea’s pretence and stays true to her despite her apparent infidelity. In the meantime, Egeo is angry with Medea for torturing his intended. Medea then discovers that Teseo is Egeo’s unknown son, something that initially no one knows but her. To avenge herself on father and son in one fell swoop, she succeeds in making Egeo hate Teseo and tries to persuade him to poison his alleged rival, thus killing his own son. The assassination attempt fails at the last minute when Egeo recognises his son from his sword, which he himself had once given his son as a gift. The family now reorganises itself: Egeo forsakes Agilea in favour of his newly regained son, and the hopelessly lovesick Medea flees, issuing dire threats.