Working alongside Matron Pace in the Resistance hospital, Helena heals countless wounded, using her vivimancy. One night, Matron asks her to give the hospital report to the Council of Five, consisting of Luc, Ilva, Falcon Matias (head of the Faith), Jan Crowther, and General Althorne, who are meeting at headquarters, located in the former Institute of Alchemy and Science. Helena worries when Luc doesn’t show up but gives her report to the Council anyway. She explains that they are weakening and suggests that instead of “burning the bodies,” they “reanimate them and use them as an infantry” (297). The Council is incensed at this suggesting of using necromancy, which they consider to be an abomination. They declare her suggestion a violation of Orion Holdfast’s and the Eternal Flame’s principals. They suspend her from the Council and dismiss her from the hospital.

Later, Soren finds and comforts Helena. Helena knows her suggestion was a risk but can’t think of any other way to turn the tide of the war. Then Ilva and Jan call a meeting with her. They are thankful Luc didn’t hear her suggestion, because he would disavow her for it. They tell her they have decided to use her in a different way: Kaine Ferron, who is beginning to work his way up the Undyings’ ranks, wants to be a Resistance spy to get revenge on Morrough for his mother Enid’s death; he has requested that Helena act as his liaison with Crowther. They task her with seducing Kaine to make him loyal to their cause while keeping her activities a secret from Luc and her friends. A hesitant Helena agrees.

Helena sees Luc, Lila, and Soren in the Alchemy Tower. Luc is optimistic about the war, telling her about a new method of killing the Undying in which they remove the lumithium pieces from the corpses so that they can’t reanimate. Luc invites her to join him for breakfast, but Helena declines. 

In her room alone, she reflects on her new circumstances and recommits to doing whatever she can to help the Resistance, even seduce Kaine. She holds her sunstone pendant, which Ilva gave her when she became a healer for the Resistance. When she meets with Crowther, they discuss the Ferrons, who use their iron alchemy to gain immense power and wealth among the guilds and Paladia. Crowther and Helena determine that Kaine has agreed to work with them to gain power over Morrough; as soon as they have won against Morrough, he will turn on them. Afterward, Helena studies the Ferron family history at the library and resolves to make things work.

Helena goes to her first meeting with Kaine at the Outpost, an abandoned factory structure that neither side is interested in maintaining so there is no surveillance. She meets Kaine and tells him she will work with him, but she feels sick about talking to the man who killed Principate Apollo. She reaffirms his deal with the Resistance that she is his as long as she lives. He demands a kiss to test her willingness. The kiss is strange; Kaine’s body doesn’t feel human, but she also feels an odd attraction. 

Afterward, Kaine gives Helena a ring that matches his. When he has a message to pass to her, her ring will burn once; if it is urgent, it will burn twice. He tells her never to communicate with him through it and passes his first envelope of information to give to Crowther. They plan to meet again so Kaine can pass his information about the Undying to the Resistance.

Helena tells Crowther and Ilva about her encounter with Kaine. She tells them about how strange his body felt—she assumes because he is Undying. She is unsure she can use her resonance to transmute him; they reiterate the importance of her secret assignment. Crowther tells her that Kaine’s mother died as a result of his vivimancy; it is widely believed that in the womb, babies who have vivimancy sap their mothers of energy. 

Helena and Kaine meet again at the Outpose. This time, Kaine reads her memories, explaining the trick as animancy. It is painful and disorienting, and she worries about him reading her mind. He warns her that the Undying will use this trick, which they are beginning to develop, against her if she is ever captured. He offers her techniques to protect her memories.

After what she said to the Council about necromancy becomes widely known, Helena becomes a pariah amongst the Resistance. She can’t attend Council meetings and is denied information about Luc. She starts to value her time with Kaine. They continue practicing animancy. Helena notices he seems lonely, too, and asks him about killing Principate Apollo. He refuses to talk about it but indicates that he has been the subject of animacy himself, as he is being studied by Bennet, Morrough’s chief scientist.

At headquarters one day, Ilva introduces Helena to four healers that she is to train to replace her in the hospital, including Elain Boyle. Meanwhile, Helena and Kaine grow closer. One day, Kaine opens up about his arranged marriage to Aurelia and his distaste for her.

As the weeks pass, Helena hones her animancy skills. Meanwhile, she tries keeping up with the Eternal Flame’s work. One day, she runs into Luc. He is upset they haven’t seen each other and again invites her to spend time with him. Remembering Ilva’s warning to distance herself from him, Helena declines.

Helena goes to the wetlands alone to harvest herbs and medicinals, which she does often. She muses on her circumstances, unsure what to do. She hides when she sees several men and necrothralls appear. They release a creature that she realizes is a chimaera, surprising her, as she believed these creatures were extinct. She watches as the men sic the chimera on a necrothrall to test it. 

Suddenly her ring starts burning. She races to the Outpost and meets Kaine, who has an envelope for her. She tells him about going to the wetlands and the chimera, and he stresses the importance of acquiring a weapon Helena can use against the Undying if she is going to go about alone. He also reveals that he has his own chimaera and suggests that he train her in how to fight. The conversation turns heated when Kaine disparages the Eternal Flame. They argue about Kaine’s obsession with power and insistence that he owns Helena, and he turns pale before ordering her to leave.

Helena reports back to Ilva and Jan, telling them about the chimaeras. Helena used to admire Ilva and was flattered that she showed interest in her at the Institute. Now, she realizes that Ilva is manipulating and using her and she always has. Afterward, Helena muses on her dynamic with Kaine, realizing that the look on his face when she confronted him is just because he’d never realized what he was like before.

Over the following week, more chimaeras surface in the area. The Eternal Flame assembles a hunting party to fight them, with Luc leading. Meanwhile, Helena continues meeting with Kaine. She apologizes for what she said to him, but he acts unaffected. He is unimpressed when she shows him the alchemy knife she got as a weapon, but he begins to train her in combat. Helena is discouraged that she still can’t beat Kaine.

Another day, Helena is shocked to discover Kaine at their Outpost meeting spot with a missing arm. He tells her that as an immortal, his arm should regenerate. A worried Helena attends to his care, and he gradually improves. She feels warmth pass between them, confused by her feelings. She reminds herself that Kaine is not her friend.

That evening, Lila confronts Helena for being distant. She, Luc, and Soren miss her. She’s confused by what Helena told the Council but worried about the Resistance, too.

Helena and Kaine continue training at the outpost. Kaine is crueler than usual, and she leaves covered in bruises. She fears Crowther will notice and be upset, and she visits Matron Pace for help. She and Pace run into Crowther, who introduces her to another new healer named Ivy. While tending to Helena, Pace tells her not to sacrifice too much for the Resistance.

The Resistance manage to kill a chimera, and they realize that it was created through vivimancy. Helena isn’t working at the hospital anymore, so she sets up a lab in an abandoned room and begins to work on developing more advanced medicines. Shiseo acts as her assistant, and one day, she offers to let him work on his own projects in her lab. He accepts.

Over the following weeks, Helena sees less of Kaine, as he has no new information to offer the Resistance. When they do meet, Kaine informs Helena that Morrough is leaving the country, and they won’t meet for several weeks of training.

Helena informs Jan and Ilva that Morrough will be traveling with many of his Undying in a neighboring country that is allying with him, Hevgoss. The Eternal Flame plans to use the information to their advantage and begins planning their attack. In the meantime, Helena takes shifts at the hospital.

Helena is shocked by Kaine’s weakened condition when they meet again. She realized that Morrough tortured Kaine for the Resistance’s attacks on areas he was supposed to be in charge of; further, she understands that Kaine knew this would happen and gave the Resistance the information anyway. She does everything in her power to help him. She is horrified to discover that the High Necromancer has been experimenting on Kaine, and there is an alchemical array carved into his body. While he is sleeping, Helena notices scars on his body and understands how much he has suffered. When Kaine wakes up, he tells her that the array was carved into him by Bennet, with the understanding that he wouldn’t survive. Helena apologizes for everything he’s undergone, using his first name. In return, he tells her where Bennet’s new laboratory is.

Helena and Kaine meet in an alternate location to conceal the medical assistance she is giving him. She isn’t sure it’s wise to save him but feels incapable of letting him die now that he trusts her. Each day, Kaine improves, and Helena wonders how to save him, sure that he is important to the Resistance. She debates giving him her Holdfast sunburst pendant to wear, but when she takes it off, it slips, falls to the ground, and shatters. Liquid metal puddles out of the broken stone then solidifies, but when she picks it up, she can feel a “warm hum of energy coming from it” (413). She uses her resonance to push the silver into Kaine’s body. Every night he seems to improve.

One day, he shares more details of Morrough’s plans. Morrough is trying to uncover “the key to immortality,” which he promised to Hevgoss militocrats; they now support the Guild Assembly (416). Morrough is using the Undying to gain power; he puts a small piece of his bone in each of the Undying, linked to a corresponding bone in his body.

Over the weeks following, Helena continues working with Kaine and communicating with Crowther and Ilva—who still regard Kaine as untrustworthy. She isn’t sure how to feel.

Helena notices new silver streaks appearing in Kaine’s hair. He attributes them to Morrough’s experiments, but she wonders about the effects of the metal she put into him. The two continue sharing intimate conversations, promising each other not to die each time they part. They aren’t exactly friendly, but they have become a lot closer. They discuss his chimera and how he can help it to integrate the separate parts of itself so that it is in less pain.

Word spreads among the Resistance of lumithium being found in the wounded’s bodies. Resistance scout Vanya Gettlich is just one victim. From Luc, Helena learns that headquarters is using Vanya’s body to study the effects of lumithium, and she is forced to do the autopsy. 

That night, Kaine shows Helena that his condition has improved. He returns to his old self, readily reminding Helena that he is in control. During a training session, he sets a group of necrothralls on her to prove that she needs combat training. She destroys them with her vivimancy, then bursts into tears, insisting she doesn’t want any of this. He admits that he has underestimated her. Afterward, they spend the evening drinking and talking. They open up about their pasts, and he tells her that he designed the array on his back, deciding it was better to try to design his own punishment. She is surprised to suddenly find him handsome and leaves disturbed.

The Council calls Helena to the Alchemy Tower to perform Vanya’s autopsy. She posits that the experimentation done on Vanya by Morrough was an attempt to “neutralize” her resonance, but she isn’t sure it was effective. The group speculates on the potential goals behind suppressing a person’s alchemy.

Afterwards, Crowther warns Helena about getting too close to Kaine. He insists she control him using magic, not emotion. The conversation leaves her feeling more alone. 

That evening, Helena asks Kaine more about Morrough’s plans. She suggests he might be seeking the Stone of the Heavens, a mythical orb imbued with immortal powers that Orion Holdfast is told to have rescued from the last necromancer during the Necromancy Wars. Kaine is skeptical, but Helena has always believed the Stone was real.

One day, Luc finds Helena in her lab and confronts her; he has found out about her proposal to the Council. He tells her that the Resistance will win because good triumphs over evil, and she should have Faith. He asks to be involved in the studies she’s doing. Because they involve Kaine and lumithium, Helena declines. An offended Luc storms out. 

Afterwards, she races to meet Kaine. She continues to heal him from the array. When she turns to leave, he offers her a drink. She agrees, and he offers her the first real smile she has seen.

Helena and Kaine get drunk together. He asks her to take her hair down, and they share an intimate moment. They kiss. Helena is overcome with desire until they pull away, and Kaine tells her to go.

Helena says that she can’t go—it is too late, and the checkpoints have closed until morning. Helena starts crying, afraid Kaine doesn’t like her. He assures her otherwise. They both fall asleep on the sofa, and in the morning, Helena wakes un “tangled together” with Kaine. On her way back to headquarters, Helena feels guilty, sick, and confused. When she arrives back at headquarters, she sees Soren, who is surprised to see her coming in disheveled in the morning.

Back at the hospital, Ivy calls Helena into a meeting with Crowley. He takes them both down to the tunnels below the Tower, where he reveals that he keeps and tortures prisoners. He tasks Helena with healing prisoners so that he can continue torturing them for information. Ivy participates, too, delighting in the cruelty.