Circe begins telling her origin story by stating that “the name for what [she is] did not exist” when she was born. She describes how her mother Perse, a beautiful nymph, enticed Circe’s father Helios, a Titan, to marry her. When Circe was born, Perse was disappointed that her child was a girl. Perse and Helios have another daughter, Pasiphaë, and a son, Perses. Both are cruel, so Circe avoids them and prefers to sit at Helios’s feet.
Rumors circulate that Prometheus is going to be punished by Zeus because he had given humans fire against Zeus’s orders. To begin his torment, Prometheus is whipped by a Fury before an eager crowd of other immortals. After the whipping, Circe and Prometheus have a brief conversation during which he tells her that “Not every god need be the same.” Afterwards, Circe goes to her room and cuts her hand, feeling that she has autonomy for the first time.
Perse has another son, Aeëtes. When he doesn’t earn a prophecy from Helios, she rejects him, too. Circe decides to care for him, and the two become close. Aeëtes tells her that he knows of some powerful herbs called pharmaka, which grow from the blood of gods.
Helios gives Pasiphaë away in marriage to Minos, the king of Crete. On the day of the wedding, Circe sees mortals for the first time and is struck by how fearful they look. Aeëtes informs her that Helios has given him a kingdom. Circe pleads with him to bring her along, but he refuses and leaves for his kingdom. Shortly after, Perses also leaves.
Circe is painfully lonely after Aeëtes’s departure. One day, she sees a man in a fishing boat. She can tell from his scars that he is a mortal. She calls out to him and, after a few fearful moments, he relaxes, and they become friends. The man’s name is Glaucos.
Circe falls in love with Glaucos. Distraught that she cannot marry someone as lowly as a mortal fisherman, she asks her grandmother Tethys whether there is some way to change Glaucos into a god. She staunchly tells her that it is impossible. Desperate, Circe asks whether pharmaka would help. Tethys is enraged and, Circe realizes, afraid.
Now sure that these powerful herbs do exist, Circe finds out from her Titan uncles where immortal blood has fallen on the earth and brings Glaucos to one of these places. There, she cuts some of the flowers and, feeling a sense from these flowers that they are magic, she pours their sap into Glaucos’s mouth. He becomes a god. She brings him to the halls of the gods, where he gets a lot of attention from nymphs and other gods.
Glaucos becomes enamored with Scylla, a beautiful nymph. Scylla flaunts Glaucos’s presents in front of Circe, who is eaten up with jealousy. She pours some of the magical flowers’ sap into Scylla’s bathing pool with the intention to reveal her inner ugliness. The next day, Circe hears that Scylla has transformed into a horrific monster and has fled into the ocean. Glaucos doesn’t mourn the loss, and he quickly moves on to other nymphs.
Circe confesses to Helios that she has used magic, but he ridicules her claim until Aeëtes visits to confirm Circe’s statement. Aeëtes adds that he, Pasiphaë, and Perses also have these powers—they are all pharmakis, or witches and sorcerers. Helios confers with Zeus on how best to handle these unpredictable powers, and they decide to exile Circe to a deserted island, Aiaia, as she is the only one who admits to seeking out magic.
The next day, Helios drops Circe off at Aiaia. The island is lushly forested and has a house for her to stay in. She begins to practice witchcraft and explore her new powers. As she brews potions and magically tames a lion to be her companion, her confidence grows.
Hermes begins visiting the island and he and Circe become lovers, but not friends. He tells her gossip, and one day he says that Scylla resides in a strait nearby, where she eats passing sailors. Circe is sickened with guilt.
One day, Circe has a visitor: a ship led by Daedalus, an ingenious mortal craftsman under Pasiphaë’s restrictive rule. He tells her that Pasiphaë has ordered that Circe come help her through labor and mentions that they must go through Scylla’s strait. In the hopes of defeating Scylla, Circe agrees. They make it through Scylla’s strait, but the spell that Circe casts to change her back into a nymph doesn’t work.
When they arrive at Crete, Circe and Daedalus perform a cesarian section on Pasiphaë to remove her baby, which is a vicious bull-headed monster, the result of Pasiphaë’s sexual encounter with a bull. Pasiphaë orders that they not harm it. After Circe sees a vision that the Minotaur, as the monster is named, will only die many years into the future, she makes a potion that will limit its craving for human flesh to just one season of the year.
When Circe asks Pasiphaë to explain why she summoned her, Pasiphaë explains that it is because she knew that Circe could withstand pain. That night, Daedalus and Circe become lovers, bonding over their guilt from past actions and feelings of impotence against those in power. When Circe leaves Crete, Daedalus gives her a beautiful loom. Circe returns to her island, feeling lonely and trapped.
One day, another ship arrives, carrying with it Aeëtes’s daughter Medea and her husband Jason. They ask her to perform katharsis to cleanse them of evil. Afterwards, Medea tells Circe that they are running away from Aeëtes, who is trying to kill them for taking his golden fleece and for killing his favorite son in their escape. Circe notices Jason shrinking from Medea, so she privately invites her niece to stay on Aiaia with her. Medea spurns her and declares undying love for Jason, and the two depart.
Lesser gods begin sending their disobedient nymph daughters to Aiaia, much to Circe’s discontent. Shortly after, Circe’s lion dies, and she mournfully burns the body, feeling more alone than ever.
Another ship arrives, bearing a crew of supposedly lost sailors. Delighted to help, Circe offers them food and lodging. After dinner, however, Circe notices a shift in their mood when they discover that there is no man on the island. She adds a potion to their wine out of caution. After drinking the wine, one of the men chokes her and rapes her. After, Circe speaks the potion’s spell and turns them into pigs and kills them.
Circe feels broken. More boats come, and she turns the men from the ships into pigs. One day, another such ship comes, and Circe turns the men into pigs as usual. But then a man knocks at her door; he had waited behind the rest of the crew. The man, later introduced as Odysseus, doesn’t drink the wine she offers him and reveals that Hermes had given him moly, an herb to ward off Circe’s spells. Circe is intrigued by him and agrees to turn his men back into humans after she and Odysseus have sex. She then invites Odysseus’s men to stay a month to rest.
Circe falls in love with Odysseus, who tells her stories of the Trojan war and explains that Athena is his patron. He stays longer than originally planned, but he eventually leaves to return to Ithaca, where his wife, Penelope, still waits for his return.
Circe discovers that she is pregnant. She is sick throughout her pregnancy, and her labor is painful. After her son Telegonus is born, she realizes that someone is trying to kill him. Athena appears, demanding that Circe hand over Telegonus. But Circe refuses. She creates a protective spell that covers the island and keeps Athena out.
Telegonus grows up to be an adventurous boy. One day, he reveals to Circe that he has made a boat with the help of Hermes, who has been secretly visiting him. Telegonus intends to sail to Ithaca to meet Odysseus. Panicked, Circe refuses at first, but eventually relents out of love for her son. To protect him, she visits Trygon, an ancient stingray with a poisonous tail. After she tells Trygon that she would suffer the poison herself to get the tail, he offers it to her willingly, without her suffering. She takes the tail and binds it to Telegonus’s spear.
Telegonus leaves and is gone for several days. When he returns, he is in despair; when Odysseus saw him, he attacked Telegonus and accidentally killed himself on the spear. Telegonus has also brought two guests back from Ithaca: Penelope and Telemachus, Odysseus’s son by Penelope. Circe is suspicious of them, as she fears that they will try to kill Telegonus. But Telemachus tells Circe that he has no intention of avenging his father. He tells her that Odysseus had become a violent and paranoid man after his return. After being sharply interrogated by Circe, Penelope confesses that she is trying to protect Telemachus from Athena, who wants to send him on a quest. Circe agrees to host them for the winter.
The two families grow closer, with Circe especially enjoying Telemachus’s calming presence. One day, Hermes visits Aiaia to inform them that Athena requests that Circe lower the protective defenses so that she can speak to Telemachus of his quest. Upon hearing that Athena has also sworn not to harm Telegonus, Circe relents.
Athena appears and tells Telemachus that he is to go west to help found a new empire. When he declines, she offers the same quest to Telegonus, who eagerly agrees. Circe is heartbroken, but she knows that he will never be happy until he explores the world. Telegonus’s departure leaves Circe feeling hollow and acutely aware that all the people she loves will leave her in death. Struck by an idea, she summons Helios and demands that he end her exile. He initially refuses, but he angrily relents when she threatens him.
Circe prepares to leave Aiaia, first explaining several herbs and potions to Penelope and then agreeing to Telemachus’s request to join her. They go to Scylla’s strait, where Circe uses a potion and spell to turn her into stone. Circe feels relieved at last.
Circe and Telemachus become lovers. They sail toward the halls of the gods, helping mortals in small ways—mending ships and offering magical remedies—as they travel. When they approach the halls, Circe locates the hill with the flowers that she used to transform Glaucos and Scylla. She cuts several, and then they return to Aiaia.
Back on Aiaia, they discover that Penelope has taught herself witchcraft. That night, Circe makes a potion using the flowers that she cut from the hill by the halls of the gods. Imagining her future with Telemachus—in which she has children and grows old with him—she drinks the potion, hoping that it will turn her into a mortal.