The second installment in the City of Fantome series opens during a violent storm over the kingdom of Valterre. Prince Andreas Mondragon Rayere, nephew to King Bertrand IV, has spent nearly six years at the Appoline University researching the last prophecy of Saint Oriel, an ancient saint who foretold a Second Coming: New saints would rise when three towers fell during a great storm. Andreas climbs the university's clock tower, raises his arms to the lightning, and begs Oriel to choose him. A bolt strikes him through the mouth, and he plummets to earth as the tower crumbles. In the blackness that follows, Oriel whispers a single word: "Thief."
Three months later, Seraphine Marchant travels with her friend Bibi to recruit a smuggler to the Order of Flames, a rebel group Sera co-founded to produce and distribute Lightfire, a golden dust that neutralizes Shade, the lethal shadow magic wielded by the Order of Daggers, the king's covert guild of assassins, which has kept Valterre in darkness for centuries. Since the fall of the Aurore Tower in the capital city of Fantome, Sera and her allies have been hiding in a remote mountain village, but Sera's own volatile magic remains beyond her control.
Ransom Hale, now Head of the Daggers, discovers a golden rose Sera left behind while investigating his vanishing smugglers. It crumbles at his touch, stripping the Shade from his body and confirming Sera is working against him. Ransom has spent the winter grieving his best friend Lark Delano, whom Sera killed in self-defense, and suppressing his feelings for her. In Fantome, his assassination targets invoke a mysterious figure called the People's Saint. Meanwhile, Nadia Raine, Ransom's second-in-command, discovers Lark's grave has been broken open from the inside, with Sera's magical scent at the site.
At her hideout, Sera struggles with her power. During meditation, she encounters a younger version of herself guarding a locked door inside her soul; behind it, her magic whispers "Look and learn. Let me out," but the inner child slams the door shut. Theo Branch, her closest friend and co-founder of the Order, suggests Sera might be a saint, but she resists the idea.
Seeking answers, Sera visits Madame Fontaine, the former Head of the Order of Cloaks, another of Valterre's formal orders, at its headquarters, House Armand. Fontaine confirms Sera possesses 'gold blood,' the mark of the saints, and draws three tarot cards representing new saints: the Stone Maiden, the Necromancer, and the Silver-tongue. Sera draws a fourth, a red rose symbolizing rebirth but also sacrifice. As they flee after being spotted, soldiers ambush them. Sera, Theo, and Bibi are kidnapped; Val, another Flame, escapes.
They awaken in the Summer Palace dungeon and are brought before the king alongside Ransom, Nadia, and Caruso Dantes, Ransom's third-in-command. The king reveals that Andreas survived the storm, now styles himself the People's Saint, and is rallying rebels with ties to neighboring Urnica's royal family. He commands both groups to kill Andreas, then eliminate Sister Marianne, an acolyte on the Isle of Alisa with destructive powers. To ensure compliance, the king holds Bibi hostage and privately offers Ransom information about his long-lost mother and sister.
The group journeys north to the Appoline, where Andreas's study reveals obsessive writings about the saints. Sera learns from the provost that Andreas went to Marvale, Saint Oriel's birthplace. Val rejoins them as they press north. At Marvale, they encounter the Necromancer, a robed figure in a golden mask whose power renders Shade useless; Sera blasts the figure backward. That evening they infiltrate the Rose Garden, a dance hall where Andreas holds court. The prince greets Sera by name, radiating charm, and presents himself as a liberator who will destroy Shade and free the people.
Sera and Ransom retreat to an inn, where they spend the night together. Her magic dissolves every shadow-mark on Ransom's body. He also removes the skull ring of Gaspard Dufort, Sera's estranged father and the Daggers' former head. But morning reveals Marvale's true horror: streets filled with dazed townsfolk burned out from the prince's mental compulsions. Ransom witnesses Andreas forcing his cousin Talisa Mondragon to dance until she collapses. When Ransom confronts him, the prince's magic implants irresistible commands: go to the Isle of Alisa, kill the acolyte, tell no one. Ransom flees with the Daggers, abandoning Sera.
Devastated, Sera meets Andreas again. In a graveyard, the Necromancer removes his mask to reveal Lark Delano, gray-skinned but alive. Andreas explains that Sera is not a saint but a "maker": when she killed Lark, her magic simultaneously remade him with the power of necromancy. Andreas then pressures Sera to use her power on Talisa, threatening Bibi's life. Sera attempts it, but her moral resistance causes the magic to turn destructive; Andreas forces her hand down, and Talisa dies. He reveals he was never chosen by fate but waited for the right storm and "wrenched" his destiny from the sky. The Flames attempt to escape, but Andreas intercepts them, places Val under compulsion, and knocks Sera unconscious. Theo escapes on horseback.
On the Isle of Alisa, the compelled Ransom discovers the chained acolyte is Anouk, his long-lost sister, hiding under the alias Marianne Adina. Anouk's saintly power allows her to detect and mend "wrongness"; she heals the compulsion in Ransom's mind. She reveals their mother was killed by Dufort. Anouk's ability to break and rebuild matter marks her as the Stone Maiden. Caruso kills the priory's head to free her, and they learn Andreas has gone south to kill the king.
In the Summer Palace dungeon, Saint Oriel visits Sera in a dream, warning that Andreas is "a wrongness in fate's tapestry." On King's Day, Valterre's annual royal celebration, Andreas stages a coup. He compels King Bertrand to crown him and drive a sword into his own chest. Lisette, a defected Dagger, enters with 30 Shade-wielding assassins, and Andreas orders a cull of the nobility. When Bibi throws herself over the young princes, Lisette kills them all. Sera's grief shatters her bindings; she burns Andreas's face and tongue before being restrained. Theo and Tobias, an inventor allied with the Flames, arrive with Lightfire fireworks that break the Daggers' shadows and the prince's compulsions.
Ransom storms the palace. Lark reveals himself as the Necromancer, raising the dead as puppets. Nadia and Caruso choose loyalty to Lark over Ransom. Anouk tears down the ceiling. Ransom finds Sera under rubble, and they escape the burning building. On the riverbank, Andreas orders an arrow volley; Ransom takes an arrow meant for Sera and falls into the river.
Sera dives in and drags him to a sandbank. His heart stops. She presses her glowing hand to his chest, and her magic sparks a new heartbeat. When Ransom opens his eyes, they burn gold. He is now a Saint of Nightmares. His power manifests as shadow beasts matching the nightmare creatures he had drawn in a private sketchbook: wolves, serpents, and ravens woven from darkness and answerable to his will. The beasts shield them as they escape.
In the aftermath, Sera and Ransom establish headquarters in the catacombs beneath Fantome and destroy all remaining Shade, formally ending the Order of Daggers. Sera resolves to begin making saints deliberately. Fabian, a young boy Ransom earlier sent to House Armand for safety, arrives with a letter from Madame Mercure, the current Head of Cloaks, seeking an alliance. An empty chair at their table is reserved for Bibi. In the epilogue, the scarred Andreas stands on the balcony of the ruined palace, resolving to kill Sera and Ransom and claim the kingdom for himself.