Set in the world of Greek mythology, the novel retells the story of Jason, his shipmates (the Argonauts), and most centrally Medea, from the perspectives of the many women whose lives are shaped, disrupted, or destroyed by a single man's quest for glory. The narrative unfolds through dozens of mortal and divine voices, tracing the voyage of the ship Argo from the Greek city of Iolcus to the distant kingdom of Colchis and back, then forward to the catastrophe in Corinth.
In Iolcus, Alcimede, Jason's mother, recounts her family's decline. She married Aeson, the rightful heir to the throne, but his younger brother Pelias seized power. Pelias, paranoid about rivals, announces that Iolcus needs the golden fleece, a magical artifact from the faraway land of Colchis, hoping the quest will remove Jason permanently. Jason volunteers to lead the expedition. The night before his departure, the elderly priestess Iphias receives a divine message for Jason from Artemis, but the next morning the crowd sweeps her past him before she can deliver it, and the goddess plays no part in his quest.
The island of Lemnos is sacred to the smith god Hephaestus. His wife Aphrodite, furious that its people have never honored her, curses the island's men with an inexplicable revulsion toward their wives. The men abandon their families and abduct women from Thrace. When they escalate to violence, the Lemnian princess Hypsipyle and her friend Iphinoë devise a counterattack. With the help of the abducted Thracian women, the Lemnian women return under cover of darkness and kill every man on the island. Hypsipyle alone spares her father, King Thoas, smuggling him to safety.
When the Argo arrives, Hypsipyle's nurse Polyxo argues the women should invite the crew to stay, since the island needs children and defenders. Jason comes ashore, and he and Hypsipyle become lovers. The revels last until the hero Heracles, who stayed aboard, shames the men into resuming their quest. Hypsipyle asks what she should do if she is carrying Jason's child; he tells her to send a son to his parents in Iolcus, a request that would deprive her of both lover and child.
The voyage continues through tragedy. Among the Doliones, a changed wind blows the Argo back in darkness; Jason unwittingly kills the welcoming King Kyzikos, and his queen Kleite dies by suicide. At Kios, Aphrodite exacts revenge on Heracles by making a water nymph pull his beloved companion Hylas beneath a stream. The blind prophet Phineus advises the crew on the Symplegades, the Clashing Rocks guarding the Black Sea. As the rocks close around the ship, the goddess Athene rushes down unseen and pushes it through.
An interlude traces the fleece's origin. Theophane, abducted by the god Poseidon, bore him a golden ram. When the Thessalian king Athamas prepared to sacrifice his twin children Phrixus and Helle, their divine mother Nephele sent the ram to rescue them. Helle fell from its back and drowned in the strait afterward called the Hellespont; only Phrixus reached Colchis, where the fleece ended up in a sacred grove of the war god Ares, guarded by a sleepless dragon. Theophane laments that her child has been reduced in memory to an object.
The Muse Erato introduces the Colchis section, noting this is a love story rather than an epic of courage, which is why poets invoked her instead of Calliope, the Muse of epic poetry. On Olympus, Hera, Athene, and Aphrodite conspire to help Jason. Their plan: Aphrodite's son Eros will shoot Aietes' youngest daughter Medea with an arrow of desire. With Medea's formidable magical powers, Jason can survive Aietes' lethal challenge: yoking fire-breathing bronze bulls, ploughing a field, sowing dragon's teeth that sprout into armed warriors, and cutting them all down in a single day.
Medea narrates being struck by Eros's arrow with the force of a physical blow. After agonized deliberation, she takes the drug of Prometheus and rides to the shrine of Hecate, the goddess of magic who taught Medea her craft. Jason meets her there, kneels, and promises marriage. Medea gives him the drug and instructions. The next day, anointed and gleaming, Jason yokes the bulls and hurls a boulder among the earth-born warriors so they turn on each other. Aietes, who never intended to surrender the fleece, walks away in silence.
That night, Medea flees to the Argo, demands Jason renew his promises before witnesses, and leads him to the sacred grove. She drugs the dragon and takes the fleece herself, carrying it to Jason. The Colchians, led by Medea's brother Apsyrtus, pursue the ship. Jason and Medea lure Apsyrtus to an island and Jason kills him. The ship's sacred oak plank commands them to seek purification from Circe, Medea's aunt, a goddess and witch who cleanses them but orders them to leave. Among the Phaeacians, Queen Arete ensures Medea cannot be returned to Colchis by arranging a marriage.
Back in Iolcus, Medea engineers King Pelias's death, tricking his daughters into killing their father by demonstrating a false miracle of rejuvenation. Jason and Medea are exiled, eventually settling in Corinth with their two sons and infant daughter. Jason befriends King Creon and his daughter Glauke, who becomes infatuated with him. Jason tells Medea he plans to marry Glauke, claiming their marriage is invalid because Medea is not Greek. Creon decrees Medea's banishment; Jason insists the children remain with him.
Medea secures sanctuary in Athens from Aegeus, the aging Athenian king, in exchange for interpreting an oracle. Then she prepares a golden dress and crown laced with lethal poison, sending them with her sons as gifts for Glauke. The princess puts them on and dies in agony. Creon embraces his daughter's body, and his flesh fuses to the poisoned garment.
Medea hides with her children on the Acrocorinth, the rocky citadel above Corinth. Jason arrives with Corinthian soldiers and redirects their fury toward Medea, calling her a foreign murderess who used her own children to deliver the poison. The soldiers resolve to kill Medea and her boys. When the younger son cries out for his father, Medea sprints to her children and pours every drop of magical strength into holding the armed men frozen. Her grandfather Helios, the sun god, sends a divine chariot but delivers a devastating condition: Jason's sons, having carried the poison, are impure and cannot ride. Medea must flee with only her daughter, or all three children die. She kills both sons, then boards the chariot.
The final chapter is narrated by Eriopis, the daughter Medea saved. She explains that Greek grammar renders girls invisible when boys are present, so no one knew Medea had a daughter. Jason never seeks Eriopis out; he returns to Iolcus and dies when a rotting plank of the derelict Argo falls on his head. Medea goes to Athens, marries Aegeus, and eventually returns to Colchis, becoming queen after her father's death. Now old, her mind sometimes fails. She speaks of her dead sons as though they are alive. A few days ago, she catches sight of two young men in the courtyard and calls to them. They come to her, and she whispers that she still loves them, and always will.