In the Quentis castle’s art gallery, Caspia sees a mural depicting a swift with the exact same scars and chipped beak as Bisten, a beloved swift who lived in her home palace in Nelfinex—yet the painting presents the creature as a bloodthirsty monster in the midst of slaughter. Andreas tells her that the artist witnessed the last migration and has spent his life painting the crux. The realization that the swifts of Nelfinex are Calandra’s feared crux overwhelms Caspia, and she becomes physically ill. She asks to visit the castle library for answers.

Andreas leads her to a vast library accessible only by royal permission. His former tutor, Faxon, the head librarian, agrees to help Caspia research her heritage in confidence. Andreas also arranges for Faxon to tutor Kos.

Walking home, Andreas tells Caspia about his younger brother, Arick, whose leg was shattered in a riding accident. Healers addicted him to korakin—a potent painkiller—and his parents refused to acknowledge the problem. A year ago, Arick died falling down the stairs while under its influence. Andreas left Quentis because his father blamed a broken cane rather than the addiction. He tells Caspia leaving was worth it because it led him to her. As he leans in to kiss her, the thrum of the ritus returns to her chest.

Aboard the fishing ship, Thora sits alone on the railing, silently grieving Mathias. Odessa approaches, apologizes for his death, and expresses gratitude. Thora replies that his death is her burden, not Odessa’s.

Ransom presents Odessa with her two knives, which he recovered in Ellder. The weapons remind her of the night of the crux attack, when she killed General Banner and  then watched as her friend Brielle was taken by the crux. She cannot bring herself to hold them. When Jodhi taunts Ransom about his disguised identity, Odessa takes the knives to prevent Ransom from retaliating, then returns them to him.

Faze scratches Ransom’s forearm, drawing drops of dark green blood from wounds that close almost immediately. Jodhi watches the rapid healing and later warns Odessa to keep the knives, as Ransom may be infected with Lyssa and thus may become dangerous. Alone below, Odessa tries to return the cuff she has worn since Ellder, but Ransom refuses, insisting that he trusts her. She admits that her faith in her father is eroding and fears he would covet the cuff if he understood its meaning. Ransom reaffirms his trust and calls her his queen as they kiss. Jodhi’s knock interrupts them. On deck, a second ship approaches, with Brother Dime standing at its bow.

The chapter opens with a flash-forward: Caspia weeps on a departing ship as Roslo’s golden castle disappears behind her.

In the present, Kos startles her out of a daze at breakfast, where she has been scratching grooves into the table. Since the thrum of the ritus returned, she has had no appetite, and a vision of herself leaving Andreas has replaced her recurring visions of Emery’s death. After Andreas takes Kos to his first lesson with Faxon, Caspia spots a ship with white sails in the harbor—the ship from her vision. She leaves a note and goes to the docks, where she finds the vessel, the Malynn, and questions its captain. When he reveals that he has never sailed nearly far enough to get her home, she leaves.

Back in the crowded marketplace, a man presses a newspaper into her hands. She unfolds it to find a full-page article about Andreas, reads it, and wanders Roslo in distress. She eventually stops before a house destroyed in a past migration, where she recognizes an older woman from a past vision in which she saw the woman, named Hali, washing green blood from her hands and speaking cryptically to a younger woman about an agreement. Not yet ready to face Andreas, Caspia lingers.

That evening, Caspia returns to find Andreas teaching Kos to sketch portraits. She notices a small drawing he made of her face from memory. After sending Kos to bed, Andreas draws a footbath for her blistered feet. Caspia presents the crumpled newspaper given to her in the marketplace, and Andreas admits he is betrothed—his mother arranged a political marriage in his absence. He does not love the woman, is trying to void the contract, and acknowledges that he should have told Caspia himself. Rather than argue, she kisses him, and they spend the night together.

Afterward, her composure breaks completely, and she cries for the future she thought they would share. Andreas holds her and apologizes until she falls asleep. When she wakes in the dark, she moves to the balcony and spends the rest of the night staring at the Malynn in the harbor, resisting the thrum in her chest.

The group is escorted to a suite in the castle’s west wing—the area reserved for guests the king wants out of sight. Odessa corrects the stewards when they address Ransom as “sir,” demanding instead that they call him “Highness” to acknowledge his status as crown prince of Turah. Faze sends the servants fleeing. After baths, Ransom and Odessa are finally alone. She is stung by her father’s cold reception and notes that he showed no visible surprise at learning that Ransom was in fact the crown prince and her husband.

Ransom concludes that King Ramsey has deliberately kept news of the crux scout within Turah, leaving the rest of Calandra unprepared for the early migration. He also hints that the creature in Ellder may not have been a scout at all, then refuses to elaborate. He declares that he will go to Allesaria alone to stop his father, leaving Odessa and Evie in Perris. Odessa refuses, invoking his own promise to stay together. She sees dark veins spreading from his sternum—a sign of the Lyssa infection—and realizes they have grown since Ellder. Unable to resolve the dilemma, Ransom decides they will address it in the morning. They spend the night together.

Caspia has a vision of Andreas with a fair-haired baby boy—a son she knows is not hers. For the 11 days since learning of his betrothal, she has kept her distance from him, spending long hours alone in the castle library without finding answers.

Andreas delivers a message from Faxon: A potential source of information has agreed to meet her at the library. He warns her the man is a priest and may appear unsettling. At the library, Caspia feels a sharp prickling across her skin and watches books float through the air toward Faxon on a ladder. A tall figure in burgundy robes emerges from the stacks. Caspia immediately recognizes him as a Velvi’os-telfer, a people known in Kenn as persecuted refugees from a war with Beesa. Andreas introduces him as Brother Nold. As the priest approaches, the pain in Caspia’s body becomes unbearable, and when he reaches out to catch her as she collapses, she screams and loses consciousness.

The morning after their arrival, Odessa is awakened by Evie screaming. In the parlor, her half-sister Mae stands with daggers drawn, facing Evie and Faze. Evie bit Mae’s leg when Mae tried to take Faze. Odessa forces Mae to put the knives away, threatens her with embarrassing gossip to deter future interference, and hugs her despite Mae’s resistance. Mae notes that Odessa seems different.

A steward summons them to breakfast with Queen Margot. The Mavins’ rooms are already empty. Margot receives the group with formal coolness but treats Evie with surprising warmth. Through the dining room window, Odessa watches her young half-brother Arthalayus (Arthy) fly an orange-feathered kite while a black puppy races alongside him. Odessa recognizes the entire scene—the fair-haired boy, the bird kite, the dog—from a story in Luella’s journal. When Arthy bursts inside and announces that he has named the puppy Titus, the match is confirmed.

General Hawksley, who has replaced Banner as the head of Quentis’s legion, arrives and summons Odessa alone to the king. Her former nursemaid Nathalia warmly embraces her first. On the throne room balcony, King Cross demands her report on Allesaria. Odessa tells him about the crux scout and the Lyssa infection. He dismisses Lyssa as not Quentis’s problem but reluctantly grants access to his healers. When she asks if he will ever trust her with the truth, he answers without hesitation: No.

Caspia wakes on a library divan to Andreas angrily demanding an explanation from Brother Nold. The priest’s proximity causes prickling pain and a pounding headache; when she tells Andreas, he orders Nold to step back. Caspia tells Andreas that the people called the Voster in Calandra are the Velvi’os-telfer—a persecuted people from her home continent of Kenn, nearly exterminated by the Beesa kingdom centuries ago. In Kenn, the Velvi’os-telfer don’t have magic as they do in Calandra. Caspia can feel the priest’s magic as an excruciating pain in her body.

Faxon arranges for Caspia and Brother Nold to speak from opposite sides of the library’s second-floor mezzanine, where the distance makes the pain tolerable while unusual acoustics let them hear each other clearly. Brother Nold confirms he has been in Calandra since before the war in Kenn ended, implying that he is unnaturally long-lived. He reveals that three of Caspia’s Starling ancestors helped his people escape to Calandra. Two of those ancestors were trapped in their shifted forms on this continent; one of them killed countless people before disappearing—almost certainly the origin of the law forbidding Starlings from crossing the Marixmore. Crucially, he confirms that the crux migrations to Calandra did not exist before his people and those Starlings arrived.

He does not know why the Voster gained magic here. His magic causes Caspia pain because, as a Starling, she does not belong on this continent. As the ache deepens, he warns her plainly to leave before it is too late, then departs. Caspia that senses she will not see him again.

Caspia has a vision of herself transformed into a crux, standing over slaughtered bodies on a marble floor. She watches herself kill Andreas even as he professes his love. The vision convinces her she must leave to prevent it from coming true.

On the balcony, she implies to Andreas that she is going, and he understands immediately. He reveals that the Malynn belongs to his family and that its captain will take her wherever she directs. He cannot leave with her. They spend one last night together. At dawn, Caspia dresses in her old traveling clothes, takes Andreas’s coat, and walks to the docks. The captain agrees to sail. As the crew prepares to cast off, she realizes that the thrum of the ritus has gone completely silent. Without it, she cannot navigate home—yet staying risks Andreas’s life. As she prays for a sign, Andreas runs down the dock toward her. He begs her to stay, insisting that no complication matters anymore. She understands that his choice to come after her is why the thrum stopped—she was never meant to leave. She agrees to stay.