Xül arranges an audience with his father. Thais convinces Morthus that both she and her brother are committed to killing Olinthar and support Morthus’s vision of a universe where gods use their power to help mortals, not exploit them. She helps Morthus see the flaws in his plan to kill Thatcher, who is “possibly the only being strong enough to actually challenge Olinthar” (582).

With some persuading from Osythe, Morthus agrees to spare Thatcher’s life on the conditions that Thatcher swear a blood oath to the resistance, choose to dwell in Sundralis after he ascends to be a more effective spy, and agree to let Morthus kill Olinthar when the time comes.

Alone, Thais and Xül ask each other how much of their relationship was real and how much was merely to advance their hidden agendas. Xül swears that he would have found a way to save Thatcher even if that meant acting against the resistance’s wishes, but Thais isn’t ready to forgive him.

The next day, the seven surviving contestants are summoned for the fourth and final Trial. Thais quickly tells Thatcher everything she’s learned about the resistance and their conditions for sparing his life.

Vorinar and Aella instruct the contestants to find their thread in the Tapestry of Fate, obtain their Token of Destiny, and reach the Library of All Things before dawn. They also warn that entering the inner sanctum where the Loom of Destiny rests is punishable by death. Thais and Thatcher find their threads, but they’re so intricately knotted together that they’re nearly impossible to extricate. As Thais follows a strange gray thread that’s tangled with the twins’ threads, another contestant shoves her into the inner sanctum.

Above the Loom of Destiny, Thais sees a veil that shows glimpses of other worlds. She sees a young woman with gray hair and “blood-red” eyes holding off an army of monsters. Suddenly, all of the contestants and their mentors are transported back to the space where the Trial began. Vorinar, his eyes “flat,” announces that an error has occurred and that all four of the remaining contestants will proceed to the Forging the next day.

While everyone’s distracted, Xül finds the twins so that they can complete the blood oath. Thatcher swears to help bring about Olinthar’s downfall, but he refuses to bind himself to Morthus and demands that Chavore be spared. Suddenly, a fissure opens in the ground and swallows Thatcher. Xül saves him, and Chavore shakes his rival’s hand in gratitude.

Thais and Xül return to the Bone Spire. When she describes what she experienced in the inner sanctum, he realizes that she saw the Cursed Lands of Vaerhuun, which have been separated from their realm for millennia.

Xül declares that he loves Thais and that he’s willing to defy his father and call off his marriage to Nyvora. They have sex in his study before retiring to his bedroom. Thais explains that she’s decided to choose Sundralis when she ascends so that she can be close to Thatcher and help bring about Olinthar’s downfall. Although Xül worries for her safety, he accepts the logic behind her strategy. She assures him, “When this is over, […] we’ll have all the time in the universe” (627).

Later that night, Xül recites an incantation over Thais. The next morning, Lyralei and the Dreamweavers prepare her for the Forging. Thais thanks Lyralei for warning her about the drink, which would have impaired her completely during the third Trial. Lyralei urges her to be careful.

Thais and Xül take a portal to Sundralis, where all of the Aesymar have gathered to watch the Forging. Thais, Thatcher, Marx, and Vance take their places on stone plinths. Olinthar explains that “the pure light” of his realm “will burn away their mortality and reveal what lies beneath” (644).

The light painfully transforms Thais, and she clings to her memories of Thatcher, Xül, Sulien, and Saltcrest so that she won’t lose her sense of self. When the light fades, she sees that everyone besides Vance survived. The new gods’ senses are heightened, and their eyes are golden.

Olinthar calls the newly ascended gods forward so they can select their domains. Marx chooses Draknavor, and Olinthar is pleased when both twins choose Sundralis. A celebration to mark their ascension commences, and Thais and Marx excuse themselves to talk in private. Marx asks, “Do you ever wonder if we’ll forget? What it was like to be mortal? To be afraid?” (656). Thais promises her that they’ll help each other remember.

Suddenly, the psychic link between the twins disappears. Thais asks Chavore where Thatcher is, but he’s disoriented and can’t remember. Using her heightened senses, Thais follows Thatcher’s trail to a hidden chamber under Sundralis where she finds “a swirling, black vortex” (660). She leaps through.

Thais enters a temple and finds a hooded figure holding a knife over Thatcher, who is bound and unconscious. Thais attacks the figure, who reveals that he is Moros possessing Olinthar’s body. Moros sent priests to Saltcrest because he knew that Thatcher had inherited Primordial power. He views Thais as an unfortunate complication in his plans and tried to kill her by sending Kavik and doctoring her drink before the third Trial.

Moros learned all about the rebellion and about the twins’ true motives by absorbing Vorinar the day before. He plans to take Thatcher’s body as his new vessel, kill Thais, and claim that Thatcher murdered Olinthar to avenge his sister. Moros reveals his ambition to conquer all the sundered realms. As Thais tries to protect her brother, Elysia appears and stabs her in the back.

The narrative moves to Xül’s perspective. Nyvora sees him gazing at Thais’s divine beauty and reminds him that their arranged marriage is vital to the rebellion, but he tells her that the wedding is off.

Xül meets with his father in Draknavor and tells him that he’s choosing love over duty just as Morthus did for Osythe: “[T]he person I love deserves more than being relegated to shadows while I play politics with my life” (678). Suddenly, Xül is struck with pain even though he’s uninjured. Furious, Morthus realizes that his son has permanently bound his soul to Thais’s through the Sev’anarath ritual. Xül explains that he never intended for anyone to know, not even Thais. Unable to reach her through a portal, he sends her some of his life force instead.

The narrative returns to Thais. She pulls Elysia’s poisoned blade out of her back, creates a star to disorient Moros and Elysia, and helps Thatcher break free. As her twin battles with Moros, she fights with Elysia. The Legend explains that she serves Moros because she felt overlooked by her fellow gods and because she hungers for power. Thais kills her by driving a blade of starlight through her chest.

Together, Thais and Thatcher fight Moros and force him to leave Olinthar’s body. Moros’s dispersed, shadowy form opens a rift into the abyss between realms and drags Thatcher through. Olinthar lies dying of wounds inflicted during the twins’ battle with Moros, and he uses his last breath to taunt Thais: “I live on in you. […] You’ll never be free of me” (696). She kills him with a star-blade.

The narrative moves to Xül. He and Morthus reach the temple just as Thais kills Olinthar. The power and authority of the King of Gods transfer to her. She explains the battle with Moros and its aftermath and then goes numb due to shock.

Morthus says that they must convince the Aesymar that he was the one who killed Olinthar because he has powerful allies and centuries of experience navigating divine politics, whereas Thais has “nothing but raw power she can’t control and a target on her back” (703). Morthus threatens to kill Thais unless Xül agrees to marry Nyvora and shore up their alliances, and Xül is forced to agree. Morthus uses his death magic to mangle Olinthar’s corpse so that the Aesymar will believe their story.

The narrative returns to Thais. Xül and Nyvora’s wedding is held two weeks after Olinthar’s death. Instead of attending, Thais visits Saltcrest in disguise and numbly watches the villagers celebrating Olinthar’s demise.

After the ceremony, Xül joins Thais on the seaside cliff where she once called down the stars. He apologizes for everything that’s happened, asks her to allow him to help her bear her grief, and says, “My heart will only ever beat for you” (713).

When Moros died, Vorinar died, too. At Morthus’s invitation, Heron becomes the new Aesymar of Fate. He visits Thais’s new home in Sundralis and tells her that he had a vision about Thatcher: “[I]n thirty-six years, for exactly seven seconds” (719), he will return to their universe. For the first time since she was separated from her twin, she begins to feel hope.

The narrative moves to Thatcher. He and Moros fall through the abyss. After an indeterminate length of time, they land in a prison created by the Esprithean pantheon. Using the power he stole from Vorinar, Moros looks into the future and predicts that Thatcher will inadvertently help him escape from the prison by finding a woman with “opalescent eyes and hair spun of moonlight” (724).

The prison’s magic prevents Moros from absorbing Thatcher’s power, but the Primordial steals his memories until he forgets Thais and his own identity. Queen Andrid Valtýr finds Thatcher and offers him a place in her realm. He can’t remember his name, so she calls him Aether.