Gabriel recounts that he entered San Maximille with Lachlan, Charlotte, Aaron, and Baptiste. Voss explains his war is a cure for eternal boredom and that Gabriel, as a worthy adversary, makes him feel alive. He reveals the Esani cult’s true purpose: not to end daysdeath, but to trigger Judgment Day as a “loophole” for damned vampires to have their souls judged alongside mortals. To himself, Gabriel thinks that the problem with triggering Judgement Day is that everyone dies. Meanwhile, Voss tells him that since he is damned regardless, he seeks to stop the Esani. He reveals his half-brother was the Redeemer, making Dior distant kin. After telling Charlotte she is pregnant, Voss grants them two days to decide if they want to join his cause, but first Gabriel must see Patience.

Gabriel is intercepted by Nicolette Chastain, Empress Margot’s niece and ambassador, who tries to recruit him; he dismisses her. At Patience’s room, Morgane assures him the child is safe. Inside, Gabriel finds disturbing violent drawings by Patience. When Patience wakes, he sees only his angelic child. They share an emotional reunion, and she asks him to sing her to sleep. In the present, Gabriel refuses details but confirms he sang their old lullaby.

Gabriel rejoins his friends. Lachlan and Charlotte refuse to align with Voss, with Lachlan warning Gabriel he will never be forgiven for this travesty. Aaron argues they should ally with the vampire as Voss’s warning about the Esani must be taken seriously. He rejects personal salvation, choosing to protect the world for Baptiste’s sake. Gabriel sides with Aaron, accepting he will die “unforgiven.” The next morning, Charlotte and Lachlan’s forces depart for León. Gabriel gives Charlotte his mother’s journal and shares a painful farewell with Lachlan, who tells him how to infiltrate Augustin through the pumpworks.

Gabriel explains Voss’s army marched south to Augustin to stop Maryn. Gabriel would enter the capital alone while Voss held Patience and Baptiste as collateral. Aaron, unable to survive the fresh-water route, stayed behind. Aaron gives Gabriel a flask of his blood. After a final farewell with Patience, Voss gives Gabriel a two-day deadline to achieve his goal. Gabriel realizes Voss himself created daysdeath. Jean-François interrupts to ask that if Voss was the maker of daysdeath, why did the twilight not end with him. Gabriel asks the historian to be patient.

Jean-François turns to Celene, who recounts attending Dior’s wedding feast with Maryn. Wrestling with her conscience, Celene dances with Dior and confesses Maryn’s deception. Dior reveals she already knows, stating that Celene’s confession saved her life. As Maryn senses that Celene has betrayed her to Dior she creams in anger. A knight, revealed to be Gabriel, attacks Maryn with a blade anointed in Dior’s holy blood. Though the blade shatters, the blood sets Maryn ablaze. She transforms into moths to escape, but Dior uses sanguimancy to hold the moths still until they are consumed by holy fire. Gabriel and Dior share a tearful reunion. He wants to kill Celene, but Dior stops him.

In the present, Gabriel explains how Dior uncovered the truth. Suspicious after Reyne’s murder, Dior secretly visited Gabriel in his cell on holy ground, where Maryn couldn’t spy. She and Gabriel orchestrated the confrontation with Phoebe; the inquisitors who subdued Phoebe were secretly loyal to Dior, and Gabriel drank Phoebe’s blood before the feast so it would power him. Back in Gabriel’s story, Empress Isabella confronts Dior, but Philippe defends his bride. Dior returns her ring, confessing to the court she was deceived. Her followers, led by Joaquin, reaffirm loyalty to her. Warning bells signal the arrival of Voss’s army.

Gabriel rushes to free Phoebe, traumatized from being enthralled by Maryn. She apologizes to Gabe for stealing his sword. Dior comforts her. When Phoebe learns Celene was spared, she is enraged since she recalls Celene shattering Ashdrinker. Celene appears, and Phoebe slaps her but declares they have a war to win. The group marches to the northern walls.

Duke Maarten commands the defense. Voss arrives to parley, threatening the soldiers’ families before offering to withdraw in exchange for Dior. When she refuses, Voss offers Gabriel the return of Patience, Aaron, and Baptiste for Dior; Gabriel spits in defiance. Maarten springs a trap by igniting oil in the drymoat, but Voss, reading his mind, triggers it early with his own archers, rendering it useless. The Dead charge.

The initial assault is a slaughter. The tireless Dead overwhelm the defenders, forcing a chaotic retreat toward Lastbridge, the last hold. In the present, Celene reports her scout moth is still flying toward Voss’s camp.

The defenders regroup at Lastbridge. Maarten launches a counterattack, luring the Dead into streets rigged with black ignis. The explosions devastate Voss’s vanguard, and Philippe commits reinforcements from Rive Cœur. Gabriel realizes things seem too easy and understands Voss has laid a trap; a second army led by Kestrel attacks their flank. Gabriel punches Maarten and takes command, organizing a fighting retreat. Kestrel and Ettiene, son and daughter of Voss, engage the heroes. Joaquin shoots Kestrel, and Gabriel fatally wounds Ettiene, but Kestrel recovers and kills Phoebe before Gabriel’s eyes.

To save trapped soldiers, Celene fights her way into the Cœur gatehouse and opens the gate, allowing the Dead to flood in. On the bridge, a grief-stricken Gabriel attacks Kestrel but is defeated and thrown to the riverbank below. About to be killed by wretched, he is saved by the arrival of Lachlan and Charlotte’s army. Charlotte reveals Gabriel’s parting gift contained a hidden plea for help.

With León reinforcing, the defenders push back. In Rive Cœur, Celene leads Dior to the Ironmongers’ Guildworks, where Dior orders them to heat the water in the canals. Meanwhile, Aaron and Baptiste escape Voss’s camp with Patience. During battle, Kestrel kills Charlotte. Lachlan, mad with grief, attacks recklessly, allowing Kestrel to read his mind and kill him easily.

On a riverbank, Aaron and Baptiste are cornered by Morgane. She reveals Voss’s ultimate goal: with Dior’s blood, he can perform a ritual to turn anyone into a highblood. She offers to turn Baptiste so he and Aaron can be together forever, and Baptiste is tempted. At the crossroads, Gabriel is nearly killed by Kestrel when Dior’s plan comes to fruition. The canals erupt in holy steam, burning the Dead. Kestrel flees as the Endless Legion is destroyed. On a rooftop, Voss, who survived, captures the exhausted Dior, killing Philippe and her guards before escaping.

Gabriel learns from Maarten that Dior has been taken. He goes to Isabella to request horses and supplies. Isabella, grieving Philippe and still harboring a decades-old grudge against Gabriel for choosing his wife Astrid over duty, furiously refuses. She forbids any soldier from leaving to help him.

Gabriel leaves Augustin but finds his horse Argent and Aaron waiting. Aaron reveals Voss has captured Baptiste, who was tempted by Morgane’s offer, and Patience. Voss’s plan to create new highbloods can only be performed at a specific location. Gabriel realizes it is Charbourg. Joaquin appears with supplies, defying Isabella’s orders. The three ride north. In the present, Jean-François wants to conclude the tale. Celene, however, insists on one last anecdote, revealing she was present for the final confrontation. Jean-François agrees.