In May 2100 on Crete, Alexis Hert prepares to leave her adoptive parents, Hades and Persephone, for the Assembly of Death. Weeks earlier, she observed Hades return from a mission to kill Titans. He was covered in blood from humans, which he considered acceptable casualties. Persephone, whose unique land-based powers let her feel everyone on Crete, pleads with Alexis to stay safe. Charlie, Alexis’s adopted brother, stands beside Persephone in silent support.

Alexis, whose real name is Hercules, is blind in her left eye, and her left ear is permanently damaged from childhood abuse—a secret only Charlie knows. She struggles with auditory hallucinations from those she has killed, which nearly give her a panic attack. Her serpent protector, Nyx, hides under her toga while her misshapen protector, Fluffy Jr., stays at her feet. All Spartans have mythical animals as protectors who can turn invisible or visible at will.

Hades waits for her, accompanied by his three-headed dog, Cerberus. He reinforces that survival requires power and fear and that Alexis’s poisonous power will make her excel at the Gladiator Competition. Rejecting safety, Alexis resolves to make her husbands pay for trapping her in marriage.

Hades “leaps” (teleports) them to a frozen Siberian forest where six Chthonic assassins wait: Alexis’s hostile husbands, Kharon and Augustus; her mentors, Achilles and Patroclus (“Patro”); and Hermos and Agatha. Kharon silently mocks her. Augustus activates his powers, blood dripping from his crimson eyes. Kharon’s mother, Artemis, whose power is terror, arrives and explains the induction hunt: survive 25 miles through the woods or die if captured. Alexis and Drex, an exiled Olympian, sprint into the icy woods.

Kharon and Augustus hunt through the frozen forest. Kharon reflects on his disgrace after losing at the Spartan Gladiator Competition years ago, when his mother disowned him for failure. Augustus found him broken and helped him prepare for the crucible.

The hunters pursue Alexis and Drex. When Hermos, a Gorgon, shoots Drex and then Alexis, Kharon immediately shoots Hermos in retaliation, leaving him critically injured. Alexis grabs the injured Drex and drags him through the woods despite her wound. She and Drex reach the clearing where Augustus, Patro, and Achilles converge, all vying to capture her.

To escape her pursuers, Alexis leaps to the tree line; when she prepares to leap again while injured, Kharon grabs her, and she leaps them together to Montana. They argue about the marriage and betrayal. Afterward, Alexis insists that their relationship is just physical, enraging Kharon.

Alexis shoots at Kharon and misses. She then successfully uses a taser on him. To her shock, he manages to pull the taser off him while being electrocuted. He grabs and kisses her. Augustus appears and orders Kharon to kiss Alexis, aroused, and then tells them to stop. Also aroused, Alexis again insists that it’s just physical, angering Kharon. Augustus scolds them both. Despite warnings about her injuries, Alexis leaps away a third time, leaving her disoriented in the Cretan dungeon, where she hears a woman screaming.

Twenty-four hours later, at the Siberian outpost, Augustus tries to see the injured Alexis. Hades blocks him, revealing that Alexis’s leap left her wounded. Ares, Augustus’s father, listens coldly. Augustus experiences intense migraines that cause blood to drip from his eyes whenever he uses his Chthonic powers—a worsening condition since the marriage bond formed.

A doctor rushes out, covered in Alexis’s blood. Inside the medical room, both Alexis and Hermos lie heavily bandaged. Hades confronts Augustus, blaming him for Alexis’s injuries and calling him a disgrace. Augustus insists that he cares for her. Poco, his raccoon protector, gently guides the suffering Augustus through the halls.

After emergency sirens blare, Patro arrives with a scroll announcing that Medusa, a Gorgon born with the power of Fate, has escaped the Underworld and murdered two immortal Olympians. The federation orders everyone to stay at Augustus’s villa until she’s captured. Augustus explains that Medusa is Kharon’s sister and that her combination of Gorgon heritage and Fate powers makes her uniquely dangerous.

Hours later, Artemis brings a bruised but recovering Alexis into the room. When asked to choose mission partners, Alexis selects Achilles and Patro instead of her husbands, devastating Augustus and Kharon.

The group leaps to Augustus’s villa at Lake Como. Augustus brings Charlie to stay and study with Helen, his younger sister. That night, Alexis, Charlie, Helen, and Drex have their first sleepover together in Helen’s room for safety.

Alexis wakes from nightmares and wanders the villa. She hears screaming and discovers Ceres (the muse accused of betraying her in the previous novel) imprisoned and bleeding in the dungeon. Augustus had been torturing her for information. Ceres swears that she’s innocent and has memory loss. Alexis decides to free her.

Helen follows and helps. When they emerge, Augustus and Kharon confront them. After tense negotiations where Kharon surprisingly supports letting the women decide, Augustus reluctantly agrees that Ceres can stay in the room connected to Helen’s under guard and surveillance.

Patro and Achilles arrive and challenge the decision. Patro wants to interrogate Ceres. Helen proposes that Patro use his truth-sensing powers only to ask if Ceres assisted Theros. She answers no, and Patro confirms that she’s not lying, though he remains suspicious. That night, Alexis dreams of Death watching over her bed.

Six days before the first Titan mission, Alexis and Drex rush to the villa’s massive underground training bunker. Five masked figures—Augustus, Kharon, Agatha, Achilles, and Patro—conduct a shooting simulation with explosions, fog, and fire. Their animal protectors wait in a safe alcove.

Alexis performs terribly, unable to hit any of the fast-moving Chthonics. Augustus grows suspicious of her consistently poor aim, even though it aligns with her known partial blindness and hearing damage. During the simulation, Kharon corners Alexis and uses his Chthonic powers, forcing her to hear his obsessive and possessive thoughts about her.

Hours pass in the grueling exercise. Afterward, in the locker-room showers, Alexis notices Kharon’s heavily scarred right leg from an old injury. She also observes that Augustus has a genital piercing. Kharon confronts her, and they argue about the marriage. Augustus emerges, and they explain their sexual interests to her, with Augustus preferring to give praise, while Kharon prefers exerting dominance and control.

Patro watches Alexis emerge from the locker room between Augustus and Kharon, looking flushed. Jealousy consumes him as he reflects on being Alexis’s mentor first. He recalls the trauma of being taken by Aphrodite at 14 and tortured by Gorgons at the House of Aphrodite under the philosophy that “torture makes the man” (87).

Patro obsessively scrubs himself in the shower, spiraling. Achilles joins him and pins him against the wall. They argue about Alexis. Achilles points out that Patro is having nightmares about the Gorgons, insisting that he needs to prioritize their relationship. Patro expresses fear about the marriage law forcing them to wed an Olympian stranger, which would ruin what they have together.

They have sex in the shower. Afterward, as Patro admits that he thought Alexis might be different because she respects their love, Achilles makes a dangerous promise: For Patro, Alexis will be theirs.

On the morning of the first Titan assignment, Persephone secretly visits Alexis in the villa. She explains that Alexis carries the blood of both the House of Hades and the House of Demeter and that their power is unique because of Iasion—Persephone’s terrifying father. She hints that difficult-to-wield power will ultimately be the strongest.

In the atrium, everyone prepares for battle. Augustus kneels before Alexis and gives her an emergency pager, making her promise to use it if threatened. He presses his forehead to hers and demands that she protect herself above everyone else. Kharon loads Alexis up with extra weapons and handcuffs despite her protests.

Artemis arrives with assignments: Agatha and Drex to Canada, Augustus and Kharon to the Amazon, and Alexis with Patro and Achilles to Rome, Italy. She explains that Medusa’s escape has changed federation plans and warns of unusual Titan behavior. She gives them tags to pierce captured Titans’ lower lips for identification. Artemis warns that they cannot return until they capture their assigned Titan, and then he leaps away.

Alexis, Patro, and Achilles search the ruins of Rome for Titans. The ancient city is mostly empty, scattered with human remains. Patro dismisses Alexis’s concerns about finding Titans, saying that they haven’t been in Rome for some time.

Patro reveals that he and Achilles have been researching ways to break her marriage bond. They suggest that she use her poisonous blood power to bring Augustus and Kharon near death, which would sever the oath without actually killing them. Alexis realizes that they want to marry a Chthonic—her—to avoid the marriage law’s requirement to wed an Olympian.

They argue intensely. Patro mocks her and calls her “pathetic.” In her anger, Alexis signs while speaking, revealing that she has known Roman Sign Language since childhood. Achilles is devastated to learn that she could understand their conversations but hid this because she was afraid of him. Patro believes that she’s ungrateful for how they helped her in the crucible, but Alexis accuses them of making her feel worthless and want to die, shocking him into silence.

The trio encounters young boys who recognize and idolize the “Crimson Duo” (Achilles and Patro). As tension mounts, two grotesque Titans with massive, sewn-together wings and corpse-like features suddenly drop from a building in front of Alexis.

Alexis freezes before the winged Titans. Achilles and Patro open fire. Black Titan blood splatters across Alexis’s face as the monsters are pushed back by the assault. Their animal protectors leap forward.

One Titan stands, its body healing and expelling bullets rapidly. It spreads its massive wings and screeches before charging. The creature rams Patro into a brick wall. His head cracks audibly, and his neck is twisted at an unnatural angle. He collapses motionless in the rubble, with blood pooling behind his skull.

Achilles stares at Patro in horror, torn between pursuing the Titans and helping his lover. The monsters turn their attention to Alexis. As she runs, Achilles kneels over Patro and shoots at the Titans now pursuing her. Achilles abandons the fight, lifts Patro’s limp body, and leaps away to safety.

The two Titans launch into the air and take flight after Alexis. She is left alone in the ruins of Rome, screaming as the winged monsters pursue her from above.