Book 4 opens with the poet requesting the Muse to describe Medea’s “suffering and thoughts” since he is not sure what motives compelled her to abandon her home and people.

Furious Aietes knows that Medea must have helped Jason. Terrified, Medea considers suicide, but Hera causes her to run away with the sons of Phrixos instead. At night, she packs up her drugs and runs to Jason, promising to get the fleece for him and warning that they will have to flee immediately after: She needs his protection. After Jason swears to make her his wife, they proceed to the sacred grove. Medea enchants the dragon that guards the fleece into sleep. While she rubs drugs on its head, Jason grabs the fleece. Returning to the Argo, they prepare for immediate departure. Jason dresses in battle gear as they row out.

Realizing they have gone, Aietes rages, warning the Colchians that they will suffer his wrath if they do not bring back his daughter so that he can punish her. They set off in their ships, but Hera causes a favorable wind to help the Argonauts. Medea sacrifices to Hekate while the Argonauts ponder how to escape.