While flying over Fourth Kingdom, Slade is wracked by an overwhelming pain in his chest. His rotting heart swells violently, causing him to lose his grip on Argo. He falls from the timberwing’s back, but Argo dives and catches him just before impact, dropping him in a bog. Paralyzed by the poison spreading from his heart and on the verge of death, Slade is flooded with memories of Auren. Just as his heart is about to burst, he feels her presence surge through him. The narrative shifts to show their two souls connecting across realms, their auras intertwining as a powerful bond forms between them.

Slade recognizes that he and Auren are forming a pāyur bond, a fated connection between fae. His black aura and her golden one mix and swirl around his body. The magical bond immediately begins to heal him. The rotten skin over his heart flakes away, revealing a golden scale. Slade is fae and possesses two supernatural forms, one with spikes and rot magic and the other with scales and fangs. The fusion of his and Auren’s magic forces these two separate fae forms to violently merge back into a single, whole being. In the final surge of power, a shadowy, incorporeal dragon with markings identical to his own manifests from his body before quickly dissipating. The immense power of the transformation overwhelms Slade, and he loses consciousness.

The perspective shifts to Auren, who is being held captive in Annwyn by King Tyec Carrick. She is disoriented and in extreme pain, and her memory is fractured. She relives moments narrated in the previous book, including Carrick’s violent attacks against Wick and Emonie. The two are members of a resistance movement called the Vulmin, and they revealed to Auren that she is the rightful heir of the fae dynasty Carrick overthrew when he seized the throne. After killing and torturing members of the resistance, Carrick threatens to kill Auren so that the Vulmin won’t have a rightful heir to inspire them to fight for change. However, a one-eyed man advises Carrick against killing her, suggesting it would be more effective to use Auren as a public “mockery” to crush the spirit of the Vulmin rebels rather than turn her into a martyr. Carrick agrees to the plan as Auren, overwhelmed by pain and confusion, passes out.

Auren is imprisoned in a dungeon cell, where a woman named Una uses magic to alter her memories. Una, who has unsettling striped eyes, repeatedly tells Auren that she was a traitor to the fae who begged King Carrick for his mercy and now owes him her loyalty. With her mind full of gaps, Auren struggles to resist the false narratives being forced upon her. She retains a vague but powerful feeling that she has forgotten something important. When Auren resists, Una becomes more aggressive, slapping her and intensifying the magical assault. After Una leaves, Auren is left alone and disoriented but manages to cling to her identity, whispering, “My name is Auren Turley. And I am stronger than the dark” (39).

The narrative shifts to Rissa, who is recovering from a stab wound. Like Auren, she was one of King Midas’s concubines before Auren killed him. Rissa was wounded when Auren was abducted and brought to trial in the previous book. Osrik, Slade’s army captain, enters her room, and she struggles with her unwanted attraction to him. Believing he only stayed by her bedside out of guilt for the security breach at the castle that resulted in her injury, Rissa tries to release him from any perceived obligation to her. Osrik forcefully rejects her attempt to push him away. He carries her to a sofa, settles her on his lap, and confesses that he was truly devastated by the thought of losing her. He admits that he is in love with her and declares that he is claiming her as his. Rissa is stunned and argues, citing her cynical view of men based on her past as a sex worker, known as a “saddle” in this world, but Osrik insists he is different.

Osrik proposes marriage, but Rissa refuses, viewing marriage as an institution that legally binds and restricts women. Osrik immediately agrees to a non-traditional commitment, symbolized only by a ring, which she accepts. They begin to have sex, but Rissa falls into her old professional habits, performing for his pleasure. Osrik stops her, insisting that with him, she should only do what she truly wants and never fake her sensations. When she instinctively fakes an orgasm, he realizes it and spanks her until she admits the truth. The act unexpectedly arouses her, and he again commands her to focus only on her own pleasure. Freed by his insistence, Rissa takes control, and for the first time, she experiences a genuine and overwhelming orgasm. Afterward, she tells Osrik that their relationship is the best mistake she has ever made.

Commander Ryatt anxiously awaits word from Slade, who should have reached Ranhold by now. He is also dealing with dangerous suspicion circulating among the soldiers that Slade is secretly a fae. A messenger hawk finally arrives, but the missive is from Lu. She reports that Slade never made it to Ranhold. Worse, the fae army has already conquered the city. Lu is taking a few soldiers to intercept fae heading for Fourth’s border, while Judd and Digby are going with King Thold and his Elites to Fifth Kingdom’s port at Breakwater to destroy the ships and prevent the fae from traveling by sea. Realizing an invasion of his own kingdom is imminent, Ryatt orders his forces to prepare Brackhill for a siege. He and Osrik decide to lead a small force to reinforce Lu at the border, with Ryatt vowing to defend Fourth Kingdom to his last breath.

Osrik enters Rissa’s room to find her arguing with her friend Polly, who then storms out. Rissa is furious because Polly is abandoning her to run off with a married man and refuses to believe the warnings about the fae army. Osrik calms her down before informing her that he is leaving for the border to fight and is taking her with him for her own safety. Rissa declares she is not the kind of woman who will wait around for a man going off to get himself killed, but she quickly agrees to go rather than be separated from him. Osrik reassures the frightened Rissa that he will not die and that she is strong enough to handle the danger. They share a tender moment before she begins packing warm clothes for the journey to Fifth Kingdom.

A flashback reveals a scene from Slade’s youth. His father, a fae named Stanton Cull, confronts him in the coop for the marewings, the kingdom’s messenger birds. He tells Slade that winged creatures are naturally drawn to the boy because he comes from a family of dragon-wielders, which is evidenced by Slade’s fae spikes and scales. Cull then flies into a rage, furious that Slade has not yet manifested a dragon. To teach Slade a lesson about culling weakness, he brutally slaughters most of the marewings in the coop with his magic. He then forces a horrified Slade to use his own rot magic to kill a nest of hatchlings and their mother. Once his father leaves, Slade, consumed by hatred and self-loathing, reverses his magic, bringing the mother bird and her babies back to life. As he sets them free, he vows he will never become like his father.

Back in the present, Slade awakens to find himself freezing and draped precariously across Argo’s back, mid-flight. After securing himself, he discovers his saddle is gone. He also realizes the pāyur bond with Auren has healed him completely: His two separate fae forms have merged, and his rot has receded. New gray, gold-rimmed scales have appeared on his chest, arcing up from below his right pec to a single pure golden scale over his heart. He recalls manifesting the shadow dragon, something his power-obsessed father pressured him to do his whole life. Though he can feel Auren’s presence through the bond, he confirms he still lacks the ability to create a magical portal, called a rip, to reach her. Realizing Argo is exhausted from flying for hours while he was unconscious, Slade instructs the timberwing to land, and they take shelter in a massive, hollowed-out tree to rest.

After resting, Slade and Argo take to the sky again. Slade is shocked to discover they are not near Fifth Kingdom but have flown all the way to Sixth, near Highbell Castle. Below, a massive fae army stretches across the landscape, and the surrounding Pitching Pines forest is ablaze. Slade understands that Argo, hearing his dying wish to “get to her,” was not flying toward the rendezvous at Ranhold but was taking the most direct route to the bridge in Seventh Kingdom. Realizing he is too late to help at Ranhold and cannot turn back, Slade decides to continue toward Auren. However, before he proceeds, he resolves to first attack the fae army below and unleash his newly discovered dragon power upon them.

In her cell, Auren is tormented by Una’s memory magic. King Carrick and the one-eyed man arrive, angry that Auren’s will has not been broken. As an alternative, the one-eyed man forces Emonie, a captured member of the Vulmin resistance who has glamour magic, to assume Auren’s appearance. He tells Carrick that this double can be paraded in public. Before being dragged away, Emonie gives Auren a ring bearing the emblem of a bird with a broken, crooked wing, which triggers a fragmentary memory of Emonie and the Vulmin rebels. The one-eyed man also reveals he has placed a dampener on the back of Auren’s neck to suppress her magic. Later, a guard shoves a food tray through a slot in the door. Auren lunges, attempting to steal his sword through the opening, but fails. In a fit of frustrated rage, she grabs a piece of bread from the tray, and it instantly blackens and rots in her hands. She realizes she possesses rot magic and sees a potential path to escape.

Queen Malina and the 52 survivors from Highbell are hiding in hollowed-out trees in the Pitching Pines forest. With their food supplies gone, the group is starving. Malina decides they must risk a return to the city for supplies, and her guard, Dommik, agrees to undertake the mission alone that night. Their plans are cut short when they discover the forest is on fire and the flames are rapidly approaching their location. Malina orders an immediate evacuation. She leads the group away from the blaze while Dommik departs to find two missing hunters, promising to track Malina’s party later using a magical signal. Before they separate, he gives her a desperate kiss.

Malina leads her exhausted people through the burning forest, but the fire spreads faster than they can travel. When a falling, flaming tree blocks their path and splits the group, Malina uses her ice magic to create a temporary bridge over it so they can reunite. They finally reach the edge of the woods and see the dilapidated shanty town on the outskirts of Highbell. A survivor named Dari informs a guilt-stricken Malina that the neighborhood’s squalor is its normal state, not the result of the invasion. As Malina guides the survivors across an open street toward what they hope is a safe, abandoned building, a group of fae soldiers emerges from a nearby house.