In her quarters at the Antium barracks, Helene Aquilla is visited by her lieutenant, Avitas Harper. He brings a message from their fellow soldier, Dex Atrius, revealing that Elias traveled north with Laia. In response, Helene sends a coded message to summon a secret contact. Shortly after, Cook appears outside Helene’s window.

Cook warns Helene that the Commandant is executing a much larger plan than anyone suspects. Revealing a severe wound, the Cook demands that Helene use her unique healing ability on her in exchange for information. Helene agrees, laying her hands on the Cook and absorbing some of the pain. Once partially healed, the Cook reveals that Laia and Elias are heading to Kauf Prison to rescue Laia’s brother, Darin.

A week after parting ways with the caravan, Laia and Keenan take refuge in another rebel safe house. Keenan confronts Laia about suppressing her grief over the death of her friend, Izzi. As she shares her memories, their shared vulnerability leads to intimacy, and they have sex.

During their conversation, Laia confesses that she has been unable to access her innate ability to become invisible—now she knows she can do it, but she can’t do it purposefully. As they prepare to continue their journey, they consult a map from Elias to plan their final route to Kauf Prison.

During his first day in a cell in Kauf’s interrogation block, a young enslaved Scholar boy brings Elias food and water. The Warden enters and subjects Elias to hours of brutal torture, eventually forcing him to confess that the Commandant poisoned him. Afterward, Elias gives the kind Scholar boy a name: Tas.

When the guard, Drusius, enters the cell, he abuses Tas. Enraged, Elias attacks Drusius to protect the boy. As punishment, the Warden has Tas taken to an adjacent cell to be tortured. He orders Drusius to remain with Elias and record his reactions to the boy’s screams.

Over the following week, Laia gradually cedes leadership to Keenan. As they travel toward Kauf, they discover a mass grave of Scholars. Nearby, in the Argent Hills, they find a large, hidden army encampment.

From a concealed position, they witness captured Scholars being loaded into Ghost Wagons, named such because those who enter the wagons are never seen alive again. They overhear a Mask mention that the notorious rebel Scholar blacksmith, Darin, is already dead. Keenan concludes the Commandant is committing genocide against Scholars and marching her secret army toward Kauf. He gives Laia a new cloak to replace the one Elias gave her, which she reluctantly removes.

After an indeterminate time in his cell, Elias has a seizure that transports his spirit to the Waiting Place. There, he again sees Shaeva, who warns him about a powerful jinn king, the Nightbringer, who is attempting to reassemble a shattered, ancient Scholar weapon, the Star. Before being pulled back to his body, Elias glimpses the spirit of Laia’s friend, Izzi, waiting to pass over.

Elias awakens in his cell to find Tas tending his wounds. The boy tells him about the prisoner in the next cell, an “Artist” who has been using his own blood to draw on the walls and often cries out the name Laia in his sleep. Elias immediately realizes this prisoner must be Laia’s brother, Darin, and berates himself for taking a soldier’s word that Darin was dead.

Two weeks after leaving Antium, Helene arrives near Kauf Prison with Harper and Faris. Faris, who has been friends with Elias since they were all at Blackcliff together, leads them to a cave Elias once used as a hideout. It looks abandoned, but they discover his scims. Harper confesses to Helene that he is no longer spying for the Commandant and reveals that she had ordered him to kill Helene if the opportunity arose.

Seeking information, Helene arranges a meeting with the Warden at a boathouse. The Warden skillfully questions her, focusing his inquiries on Laia. Through his careful manipulations, Helene realizes the Warden is holding Elias captive in Kauf, a fact he then confirms.

Following Elias’s map, Laia and Keenan locate the hidden cave near Kauf Prison just as a snowstorm begins. Inside, they find Elias’s pack, but the hiding place for his scims is empty. The presence of stale food confirms Elias was there but has not returned.

As they take shelter, Helene Aquilla appears at the cave entrance with Faris and Harper. Addressing Laia by name, Helene warns her not to interfere with her plans, establishing a tense standoff.

After several more days of torture, Elias refuses an offer of help from a prison rebel group, relayed by Tas. During another seizure, his spirit travels to the Waiting Place, where he finds Izzi’s ghost and helps her find peace. Upon returning to his body, he ambushes Drusius, subdues him, and steals his cell keys.

Elias unlocks the adjacent cell and finds Darin inside. Darin reveals that the Warden has only ever questioned him about Laia, causing Elias to reconsider what the Warden wants. Darin also says something about Laia that Elias remembers Keenan saying in exactly the same words. This detail makes Elias suspect Keenan is an informant who got information about Laia from the Warden to better integrate himself into the group. Their escape attempt is short-lived, as Masks quickly discover and recapture them.

After Laia mentions seeing a hidden army in the Argent Hills, Helene realizes the Commandant has been secretly siphoning troops from the Empire. She sends Faris to scout the encampment.

That night, Helene and Harper infiltrate the Commandant’s camp and eavesdrop on her meeting with the Warden. Helene overhears them discussing their allegiance to a master they call the Nightbringer. The Commandant reveals her plan to use the secret army to march on Antium, overthrow Emperor Marcus, and seize the throne.

Back in the cave, Laia insists that any rescue plan for her brother must also include Elias. While Keenan leaves to scout the prison, Laia practices her power of invisibility, successfully disappearing for the first time in weeks.

Keenan returns with stolen Mask uniforms and news that the prison is preparing for mass executions. When Laia tries to demonstrate her power, she is unable to become invisible again. Citing her past failures, Keenan dismisses her power and insists she follow his rescue plan precisely. Feeling diminished, Laia agrees.

After his recapture, the Warden brings Elias back to his cell, using Tas as a hostage. Elias proposes a bargain: He will answer every question truthfully if the Warden answers one of his. The Warden accepts.

Elias recounts his journey with Laia. He notices the Warden shows no interest whenever he mentions Keenan. For his question, Elias asks who is controlling the Warden. The Warden cryptically evades, stating Elias should have asked what is controlling him, not who, implying that a nonhuman force is directing his actions.

The night before their planned infiltration of Kauf, Laia finds Keenan in the woods. As a gesture of love and trust, she gives him her silver armlet. The act triggers a transformation in Keenan, who reveals his true identity as the ancient jinn king, the Nightbringer.

Laia is pulled into his mind and forced to witness his memories. She sees his millennia-long quest to reclaim the scattered shards of the Star, a powerful Scholar weapon that once imprisoned his people. The shards, scattered throughout the land as silver, can only be acquired when given freely as an act of love.  Having obtained the shard, the Nightbringer casts her out of his mind and vanishes.