Grey Sister (book of the Ancestor, #2)

The second installment of Mark Lawrence's Book of the Ancestor series is set on Abeth, a dying world orbiting a fading red sun where humanity survives in a narrow equatorial strip called the Corridor, kept habitable by a massive artificial moon. The inhabitants descend from four ancient tribes whose bloodlines can manifest as extraordinary abilities: hunska speed, marjal shadow-work and empathy, quantal thread-manipulation and the power to walk the Path (a metaphysical conduit of raw energy), and gerant size and strength. The tribes also brought shiphearts, orbs that amplify magical powers. A flash-forward prologue shows Lano Tacsis, son of a powerful lord, arriving at the Convent of Sweet Mercy with an army and eight Noi-Guin, elite assassins, intent on killing Nona Grey, now known as Sister Cage.

The story opens two years after Red Sister. Sister Apple, the convent's Poisoner, races to save her lover, Sister Kettle, who has been stabbed with a Noi-Guin knife coated in lethal venom. When standard antidotes fail, Apple pushes Kettle partially into shadow, saving her life but risking the severance of Kettle's soul from the Ancestor, the nuns' faith.

Nona, now roughly fifteen, is a rare triple-blood novice possessing hunska, marjal, and quantal abilities. She carries a devil named Keot, a fragment of the Missing, the vanished civilization that once inhabited Abeth. Keot entered her skin when she killed Raymel Tacsis and feeds on her rage. Nona advances to Mystic Class, an advanced level of study, alongside Zole, an ice-tribe girl believed to be the Argatha, the prophesied Chosen One, with Nona designated as her Shield, or protector.

Nona immediately clashes with Joeli Namsis, a quantal novice from a wealthy family allied with the Tacsis. When Joeli insults Hessa, Nona's friend killed during the theft of the convent's shipheart in Red Sister, Nona pins Joeli down and grabs her throat before Darla, a gerant-blooded friend, pulls her off. Joeli fabricates evidence of strangulation using bruise-inducing ointment, but Abbess Glass, the convent's shrewd leader, convenes a hearing where Sister Apple exposes the deception. Both novices receive minor punishments.

Nona begins learning thread-work, the art of manipulating the subtle connections binding all things. She leads Ara and other friends into caves beneath the convent, where they encounter a holothour, an ancient creature of the Missing that floods them with paralyzing terror. Keot shields Nona from the creature's thread-work, which erases the other girls' memories of the caves. Nona later restores their memories through a self-taught trance technique.

The Inquisition, the Church's enforcement arm, arrives at Sweet Mercy led by Brother Pelter, installing watchers throughout the convent. On a visit to the capital, Safira, an agent of the emperor's sister Sherzal, warns Nona that the Noi-Guin still want her dead. Nona undertakes the Shade Trial, a test of stealth, using coordinated decoys to retrieve the trial's puzzle-box, which she cuts open with her flaw-blades, invisible extensions of sharpness projected from her fingers.

Returning to the caves, the novices face the holothour again. Nona stands alone against the creature to rescue the fallen Ara and forces it to retreat. Beyond the holothour's cavern, she climbs to the spot where Hessa died and discovers a single black thread: her severed shadow's connection to the shipheart stolen by Yisht, the ice-tribe warrior who served Sherzal. She takes the thread, feeling a faint link to the shipheart's power.

Joeli betrays Nona to the Inquisition, revealing that trip-threads in the undercaves detected her intrusion. Pelter argues Nona should be drowned. That night, Kettle rushes Nona from the convent. Before parting, Nona thread-binds herself to Kettle, creating a bond that allows them to sense each other across distances. Nona flees alone into the night.

Traveling east, Nona discovers her childhood village destroyed by Sherzal's soldiers and learns her mother is dead. The child-taker Giljohn ambushes her for a bounty, but Nona incapacitates him. At White Lake, an unseen attacker strikes her with poisoned darts, and she loses consciousness. She wakes imprisoned in the Tetragode, the hidden fortress of the Noi-Guin in the Grampain Mountains, fitted with sigil-worked restraints that suppress her powers.

Thuran Tacsis and his son Lano arrive, having purchased Nona. Thuran uses the Harm, a sigil-worked disc that inflicts unbearable pain. Lano cuts Nona's nostril and promises to take her fingers and eyes. Both leave for Sherzal's grand party, promising to return. Nona begins working to free the chain anchoring her to the wall.

Kettle and Zole track Nona to the Tetragode, the Noi-Guin's mountain fortress which also houses one of the empire's four shiphearts, infiltrating the stronghold using Zole's marjal empathy to influence guards. At a checkpoint, Zole kills a Noi-Guin in close combat, her first kill. Meanwhile, Abbess Glass has engineered her own arrest on heresy charges, knowing that as a former High Inquisitor she can only be tried at a royal palace, but she is dismayed to learn Pelter is taking her to Sherzal's palace rather than the emperor's.

Nona frees her chain and fights out of the cells, killing Lightless (the Tetragode's guards) and a Noi-Guin. Poisoned by blade-venom, she damages the sigils on her collar with acid, partially restoring her shipheart connection. Her consciousness leaps into Kettle's body through the thread-bond; Kettle, in Nona's body, identifies the poison and administers the antidote. Clera Ghomal, Nona's former friend now training with Sherzal's agents, rescues Nona through a secret passage. Nona walks the Path and channels devastating lightning, destroying converging enemies and reviving Kettle. The three escape toward Sherzal's palace.

At a midnight trial, Glass reveals she possesses written permission to practice the heresy she was charged with and explains she engineered her arrest to place a legitimate court where a royal family member can be tried. Sister Agika, a judge loyal to Glass, arrests Sherzal for theft of the shipheart. Joeli attempts thread-work from the gallery to sway a judge, but Ara counters her. Darla shoves Joeli from her seat, breaking the manipulation. The judges vote to put Sherzal to questioning.

Sherzal rejects the verdict and reveals her plan: She intends to gather four shiphearts to open the Ark—an ancient structure left by the Missing—and control the moon. She proposes allying with the Scithrowl battle-queen Adoma to depose her brother, Emperor Crucical, then using the moon to push back the ice while crushing rival nations.

Ara walks the Path and erupts with blinding energy, scattering Sherzal's guards. Darla is mortally wounded after Joeli uses thread-work to freeze her in combat. Below the palace, Nona, Kettle, and Clera confront Yisht, now grotesquely transformed by devils absorbed from the shipheart. Keot is expelled from Nona and enters Yisht, disrupting the devils within her. In the corridors, Nona captures Thuran and presses the Harm permanently onto his back, condemning him to endless agony.

The groups converge in the stables, where Darla dies in Nona's arms. With soldiers closing in, Nona walks the Path a second time, channeling its energy to push Sherzal's massive carriage through the gates as a battering ram. As soldiers advance on the stranded survivors, Zole appears with the Noi-Guin's shipheart, stolen from the Tetragode, and collapses a mountainside onto the pursuers. A devil-taint creeps across Zole's hand, revealing the cost of carrying the artifact. Glass commutes Nona's punishment to minor restrictions.

The epilogue returns to the prologue's timeline. Lano leads his army and the Noi-Guin, including the Singular, the order's supreme leader, against Sweet Mercy. Clera walks among them as the final confrontation approaches, the story continuing in the next volume.