In his suite, Arkyn finds Sereme waiting. He confronts her about her failure to properly report on Raeve’s trial and execution order, which she dismisses as a clerical error. Feeling her influence wane, Sereme urges Arkyn to kill Raeve in the pits. Believing her position secure, Sereme declares herself his future queen, insisting there is no room for Raeve. Disgusted by her presumption, Arkyn decides he is done with her. He leads her into the snowy wilderness, where he coldly tells her he has no use for her. As his dragon Cliár appears, Arkyn tells the terrified Sereme to run.

Pyrok wakes to find Essi gone. He finds a lark explaining that she has gone out to hunt for food for Gruffin. Worried, he spots Essi in the distance, limping and dragging a dead snow wyrm. His concern turns to alarm when he sees that she is being stalked by at least two monstrous, crow-like beasts called crowls. He arms himself and rushes outside.

Pyrok finds Essi collapsed and bleeding as the crowls emerge from the Mists. He fights, but they are surrounded. He uses his weald to summon Ignos. A whirlpool of flames erupts, incinerating their attackers. A Moltenmaw swoops down to snatch a burning crow. Pyrok turns to get Essi to safety, only to witness her deliberately walk into the wall of fire and disappear.

Believing Essi has perished, Pyrok is consumed by grief, mirroring the grief he felt after his mother’s death by suicide. As Moltenmaws swarm, his dragon, Maell, intervenes. During the attack, Pyrok is struck by a poisonous barb and slashed across the abdomen. As venom paralyzes him, he hallucinates a mythical Elding Bird rising from the fire.

Suddenly, Essi appears, unharmed. She bites her own wrist and makes him drink her blood. He feels agonizing burning heat spread through him before losing consciousness.

Imprisoned in a cell bordering Arkyn’s arena, Kaan reflects on his discovery that Kyzari is his daughter. He suppresses his fire with a cold tonic and blocks Rygun. Arkyn appears, face lit by the arena’s glow. A gate opens, and Raeve enters as the crowd chants “Fire Lark”—the name Raeve went by when she was Arkyn’s enslaved fighter, the only one to survive the pit. Her eyes are black—controlled by the Other, Slátra—and she manifests wings of fire. Arkyn tortures Kaan, stabbing him and puncturing a lung. He demands that Kaan fight Raeve convincingly, as her killing him will serve as public payment for his war crimes in the eyes of the Tri-Council. Only once Arkyn is satisfied with the show will he nod from his balcony, allowing Raeve to kill Kaan. Both Raeve and Kaan must go along with this plan if they want Kyzari and Veya to survive. To protect them, Kaan agrees to fight the woman he loves.

In despair, Veya watches over Kyzari, who is near death from her injuries. A lark arrives with a message from Kaan to Kyzari, which Veya places in Kyzari’s hand. In the message, Kaan apologizes for failing Kyzari and asks her to tell him where she is so he can come to her. Their guard is suddenly killed, and a miskunn named Uno appears to rescue them. Uno frees Veya, then detaches Kyzari’s chain but insists her iron shackle must remain if Veya wishes to survive. She warns that the Moonfall is imminent.

As Veya carries Kyzari through the tunnels, their escape is blocked by a Fate Herder. The beast licks Kyzari’s face affectionately before becoming aggressive and herding them down the right tunnel.

A wounded Kaan is thrown into the pit before a hostile crowd and watching Arkyn. He faces Raeve, possessed by Slátra. When monstrous razah creatures emerge, Slátra single-handedly slaughters them, reviving the crowd’s chants of “Fire Lark.” Afterward, they stage a duel. Unable to harm Raeve, Kaan pins her and whispers that he loves her.

When Arkyn signals the end, Slátra prepares to execute the kneeling Kaan. Just before the blow, Raeve’s consciousness returns, displacing Slátra. Instead of killing Kaan, she kisses him. As the mountain shakes, Raeve declares a new plan: They will break Kyzari and Veya out themselves. She speaks in Ignos’s language, setting every ember in the arena ablaze, trapping everyone inside.

Raeve channels Bulder and Ignos. She has Bulder crack open the arena floor, then directs Ignos to consume the mountain’s heat, plunging the cavern into darkness. Rygun appears, attempting to break through the ceiling. Raeve synchronizes Bulder and Ignos, creating a colossal magma form. She directs this entity to obliterate Arkyn’s balcony, presumably killing him. Still consumed by rage, she has the magma form punch a larger hole in the ceiling, allowing Rygun and the storm to enter. Raeve pleads with the Creators to saturate Rygun with magma to warm him; he mauls the remaining spectators. The arena is in chaos.

Forced into a blizzard, Veya carries a dying Kyzari to a sheltered outcrop. Believing Kyzari is taking her final breaths, Veya is shocked when Uno removes her shackle, the storm stops, and Kyzari awakens singing in an unknown language. An immense force throws Veya back as the Aether Stone releases silver light, forming a powerful male being. He cradles Kyzari, healing all her wounds. Veya recognizes him as the God of Aether, the Creator to whom Kyzari’s heart belonged. As he unfurls vast tattered wings and embraces the restored Kyzari, the catastrophic power of their reunion causes moons to begin falling.

Kaan pulls Raeve back from her bloodlust. They see that Arkyn has survived and is escaping on an Elding Bird. As he flees, a moon falls. Kaan gives Raeve the choice to pursue Arkyn. Raeve chooses Kyzari and departs to find her. After a fraught farewell, Kaan mounts Rygun and takes flight to hunt Arkyn.

As the world shakes and tunnels collapse, Raeve sprints through a dungeon packed with prisoners. She quickly kills two of Arkyn’s guards trying to control inmates. She tosses a keychain into a cell, instructing the inmates to free as many as they can. Raeve reveals that the moons are falling and continues on.

Kaan and Rygun track the Elding Bird, following its embers north before arcing west and south toward Netheryn. Filled with dread, he commands Rygun to stop, but the dragon roars in defiance. Rygun powers south in determined pursuit, hunting with an unstoppable drive to avenge them.

Raeve reaches the dungeons and finds Veya’s and Kyzari’s cells empty. Recovering from her despair, she finds a dead guard and a familiar button, leading her to believe they escaped. Her hope is destroyed when she finds the parchment lark Nee torn in half. Raeve is crushed by the revelation that Nee had been a message from Kyzari sent long ago, which she had dismissed—she could have rescued her daughter sooner. As tunnels collapse, Clode makes urgent contact, confirming that Kyzari is alive and needs her help. Renewed, she pockets the broken Nee and follows Clode’s call.

Riding a weakened Rygun, Kaan pursues Arkyn through a battlefield of falling moons. The cold prevents Rygun from producing flame, and Kaan’s pleas to Ignos go unanswered. After following into the Moving Mists, the Elding Bird rises and clamps onto Rygun’s neck, pecking out his right eye. Enraged, Kaan leaps onto the bird, stabs it, and puts Arkyn in a chokehold. Arkyn stabs Kaan in the abdomen. Rygun clamps his jaws on the Elding Bird and initiates a suicidal dive. Through their bond, Rygun urges Kaan to let go, but he refuses. Rygun shakes Kaan and Arkyn loose before he and the bird crash. Landing on Arkyn, Kaan beats him to death with his fists before decapitating him.

Raeve emerges onto a mountainside to witness moons falling, dislodged by the powerful connection between Kyzari and Caelis. Kyzari is manifesting Caelis from the Aether Stone on her forehead. After rescuing a distraught Veya, Raeve fights through the destructive force. Caelis reads Raeve’s soul and allows her to approach. Raeve steps through him into Kyzari’s arms. At her touch, Kyzari stops projecting, Caelis vanishes, and the cataclysm ceases. Overwhelmed, Kyzari faints. For the first time, Raeve catches her daughter as she falls.

Kaan awakens wounded; the moons have stopped falling, and Arkyn is dead. Feeling Rygun’s life force fading, he searches for him. He encounters the grievously injured Elding Bird, which approaches Arkyn’s body and transforms into a red-haired fae woman—Essi—before dying. Following a bloody trail, Kaan finds Rygun in a crater, mutilated and dying. His attempts to heal the dragon fail. Realizing they are both dying, Rygun gathers Kaan into his claw, curling his body around him on the snow. As Kaan hums a final song, a large silver-scaled dragon descends from the sky.

Raeve finds Ahvi recovering, guarded by the Fate Herder, which Ahvi claims is a friend. In an adjoining room, healer Pidra tends to the unconscious Kaan, who lies beside an unresponsive Kyzari. Raeve rests between them. Kaan wakes briefly, expressing his fear this is a dream and passing on a message that Slátra is waiting. Raeve examines her internal mindscape, finding Slátra alive but silent. Slátra reveals a single stone of marbled silver and black—both their memories melded. When Raeve asks whether the stone is why she lost herself, Slátra conveys that she was never truly lost to Raeve. Deciding to stop running from the past, Raeve takes the stone, which begins to show her Kyzari’s birth.

Elluin endures a difficult labor, giving birth to a daughter who is not breathing. The maids lose hope, but Slátra arrives and chuffs at the infant, who then takes her first breath. Elluin names her Kyzari Neván Vaegor, honoring her mother and Kaan. Elluin is drugged by a tincture. Tyroth storms in with a Bloodlace, who performs a ritual confirming Kaan’s paternity. Enraged, Tyroth orders a stone spike to impale Elluin. As she dies, he rips Kyzari from her arms, transfers the Aether Stone from Elluin’s brow to the infant’s, and leaves. Slátra returns to retrieve Elluin’s body, flies into the heavens, and sacrifices herself, planting her life essence into Elluin’s chest in the hope that Elluin might one day return to life for her daughter.

Raeve awakens protected within Slátra’s claw. Fighting bloodlust, she recalls that Tyroth murdered her and stole her newborn daughter, placing a diadem—meant for her—on the infant’s head. This solidifies her purpose: vengeance against Tyroth for Kaan, Kyzari, Slátra, and herself.

In a snowy landscape, Sereme locates an unmarked grave containing Arkyn and a redheaded fae female she doesn’t recognize—Essi. Watched by a curious Clode, she unearths Arkyn’s frozen corpse but leaves Essi buried. Chastising the body for his betrayal, Sereme performs a ritual, placing a piece of his flesh into a blood-binding vial. She douses Arkyn with spirits and sets him on fire, intending for him to rise bound to her will. As the fire transforms the corpse, a disoriented, white-haired male stumbles upon the scene. Sereme reveals she was expecting him and identifies him as Haedeon Neván before offering him food.