After her death, Mische wakes in the underworld, where she is greeted by Vincent—the dead vampire king of the House of Night. The underworld is collapsing; fissures in its barriers have created a way for monsters to leak through and feast on the souls of the dead. Vincent informs Mische that she is the reason for this. When she killed Atroxus, the sun fell, “ushering in an endless night” (25). And when she subsequently thwarted the resurrection spell for Alarus in order to spare Asar’s soul, that—combined with the absence of the now-destroyed relics that Alarus used to create the underworld—dismantled its foundations.

Vincent reveals that Asar is still alive and possesses the power of a god, which he must use to repair the underworld before it is too far gone. However, Asar is currently imprisoned by the White Pantheon (the 12 major gods). Moreover, he needs the help of Mische—who originally cast the resurrection spell—to give him the power to do it. Vincent is a messenger on behalf of an undisclosed god, though he confirms that it was not Nyaxia who sent him.

When the gods imprison Asar in a cell of complete darkness, he is reminded of lessons he endured as a young boy. His mentor, Gideon, would lock him in a dark box for days so he’d become accustomed to operating without his senses. The memory of Mische’s death replays endlessly in Asar’s mind; Mische was slain by the goddess of justice, Shiket, after being brutally burned by Atroxus.

Eventually, Shiket sends her loyal Sentinels—mortals who traded their souls for immortality—to retrieve Asar. When the Sentinels insult Mische and claim that she will be forgotten, Asar asserts that she will be remembered forever and that death is not the end for her.

Asar is led through the White Pantheon’s capital city of Ysria and brought before the gods: Vitarus, god of harvest, Ix, goddess of sex and fertility, Srana, goddess of science, Ijakai, goddess of animals, Zarux, god of sea and sky, Kajmar, god of illusion and performance, Acaeja, goddess of fate and spell casting, and Shiket. Asar eyes Shiket’s Blade of Retribution with disdain; the sword “that represent[s] a rightful death granted in a rightful punishment” was used to end Mische’s life (42).

The gods surround the circular patio outside the palace of the White Pantheon, which bears the sigil of the sun. The sigil is shattered, with “pure blackness” at its center. Asar is forced to kneel and press his hands to the sigil as the gods do the same. Their combined power begins to drag the broken pieces of the sun back together, but the light magic is too much for Asar’s vampire body to handle, and he breaks contact. The sun sigil remains fractured. Kajmar and Shiket call for Asar’s death, but Acaeja states that they should accept what fate has dealt.

When Shiket calls his death justice, Asar smiles sarcastically, stoking the goddess’s anger. They fight, but Shiket does not kill him; the reason for which becomes clear when Acaeja states that Asar has the blood of Alarus in his veins. They aren’t sure whether or not Asar is protected by the pact that all major gods made not to kill each other. As a test, Shiket kills her nearest Sentinel, and Asar lunges forward out of assumed bloodlust. To Shiket, this only further proves that he is not like them, “a slave to his desires” like all vampires (48). However, this uncontrollable bloodlust was secretly feigned so that Asar could steal a shard of the sun from the floor.

Asar is taken back to his cell, where he bides his time with the sun shard tucked against his chest. When the gods decide to kill him, they send three Sentinels, whom he kills quickly with the shard’s power. As he navigates to the exit of his prison, he hears Mische distantly calling for him. He follows the voice to a staircase leading down to a shore of golden water and ivory sand. There, Mische kneels, looking exactly as he last saw her. When he reaches for her, the sand opens beneath them, and they fall.

Asar wakes in a small room. He is unshackled and among three individuals who he soon learns are demigods. The woman with a metal jaw plate and hand of metal, Kayeh, is a demigod of Vitarus, the older man with ethereal grace and youthfulness is Kajmar’s, and the young man with black eyes and a white wolf familiar is Ijakai’s. Kajmar’s illusions of Mische led Asar to them.

Acaeja enters and dismisses the demigods from the room. She tells Asar that his and Mische’s fates are now entwined after the thwarted resurrection spell and “fraying” under the tension. Moreover, the underworld is crumbling; however, their connected fates keep Mische tethered to life. Acaeja offers Asar a choice. If she severs the connection, the underworld’s decay will slow, and Asar will keep a fraction of divine power, but Mische will be dead. If, on the other hand, Acaeja strengthens the connection, Asar must ascend to full divinity before the underworld collapses in order to revive Mische. In order to ascend, Asar and Mische must obtain and wield the three cores of Alarus’s power: his mask, his eye, and his heart. The underworld will only survive a few more weeks at its current rate of decay, but Asar accepts the challenge for a chance at saving Mische.

Mische and Vincent travel through the underworld, killing the souleaters they cross paths with. Mische suddenly collapses in pain just as the souls of the dead and souleaters in the distance begin frantically running. A hum grows louder until the sky rips open.

Asar feels the same pain as Acaeja strengthens his connection to Mische. Acaeja opens a door to the ether between worlds—the spira, which only gods can use for travel. Acaeja urges him to make haste, as Shiket will send her Sentinels after Mische as soon as she realizes that Asar has escaped. Acaeja warns that the door will only remain open temporarily, so Asar will need to return with Mische before it closes.

Mische notices a red thread through her chest when Vincent pulls her to her feet. She’s then immediately knocked unconscious by one of Shiket’s Sentinels. Mische dreams of her sister, Saescha, who regards a dead firefinch with maggots in its chest and complains that it’s not worth saving despite Mische’s belief that it is a phoenix and still has much to do.

Mische wakes in a tower with her wrists bound to a wall. The Sentinel holding her captive reveals that Asar is shredding the veil to reach Mische. The Sentinel accuses Mische of having the ego to outrun justice for murdering a god. Asar’s dog, Luce, appears and attacks the Sentinel, who raises their sword, forcing Mische to wield shadow magic against them. Luce pushes Asar’s sword toward Mische, who uses it to break her chains just as Vincent arrives, pushing the Sentinel off the edge of the tower.

Following Vincent’s instructions, Mische takes a staircase up and directly through the broken veil, surrounded by battle as the guardians try to contain the souls and souleaters in the underworld. Though Mische is doubtful and afraid, Vincent’s encouragement motivates her to begin climbing the staircase with Luce.

Asar traverses the spira, which deposits him at the veil to the underworld. He is greeted by the lioness who guards the gate. When she does not let him pass, he rips it open by force.

Mische’s body grows heavier the higher she climbs. When she sees Asar at the top, striking the veil repeatedly to get to her, she climbs faster but is intercepted by the serpent guardian, who won’t let her leave. Mische withdraws Asar’s sword and slashes open the veil, which allows Asar to pull her through.