The Locked Tomb, #1
Gideon the Ninth
by Tamsyn Muir
Contents
Overview
Gideon the Ninth follows Gideon Nav, an indentured fighter raised in the bleak Ninth House, who wants only to escape servitude and join the Cohort. Her plans are derailed by Harrowhark Nonagesimus, the brilliant, hostile heir of the Ninth, when an imperial summons calls Harrow and a cavalier to the abandoned First House to compete for the chance to become Lyctors, the Emperor’s immortal servants.
Forced into the role of Harrow’s cavalier, Gideon must pretend to be a properly trained noble swordswoman while navigating Canaan House, a beautiful ruin filled with rival heirs, hidden laboratories, locked doors, and dangerous secrets. The story blends locked-room mystery, necromantic science, swordplay, and dark humor while exploring loyalty, ambition, sacrifice, trauma, and the strange intimacy between necromancer and cavalier.
Plot Summary ⚠️ Spoilers
Gideon Nav, an unwanted ward of the Ninth House, makes another carefully planned escape from Drearburh, hoping to leave on a shuttle and enlist in the Cohort. Her attempt is blocked first by Crux and Aiglamene, then by Harrowhark Nonagesimus, the Reverend Daughter of the Ninth. Harrow manipulates Gideon with a genuine Cohort commission and defeats her in a rigged duel using bones hidden in the drillshaft. At the House muster, Harrow reveals an imperial summons: she and her cavalier are invited to the First House to attempt Lyctorhood. When Ortus Nigenad, Harrow’s official cavalier, flees with his mother on Gideon’s shuttle, Gideon is stranded. Harrow turns the disaster into an offer: if Gideon serves as her replacement cavalier, Gideon may finally earn freedom.
Gideon trains for three months under Aiglamene, learning enough rapier work and formal bearing to pass as a cavalier while Harrow studies obsessively and hides the Ninth’s weakness, including the fact that her parents are long dead. The two leave for Canaan House, a ruined palace on the First House, where Teacher welcomes the gathered necromancers and cavaliers. The candidates are told only that the Emperor needs new Lyctors and that they must not open locked doors without permission. Harrow quickly realizes the rule is a clue and begins mapping the House’s hidden lower facility, stealing Gideon’s iron ring and investigating alone until Gideon finds her unconscious in a bone cocoon and forces a reluctant partnership.
As the Houses explore, Gideon meets rivals and allies: Palamedes Sextus and Camilla Hect of the Sixth, Abigail Pent and Magnus Quinn of the Fifth, the Fourth teenagers Isaac Tettares and Jeannemary Chatur, the Third House twins Coronabeth and Ianthe Tridentarius with their cavalier Naberius Tern, the militant Second House pair Judith Deuteros and Marta Dyas, the severe Eighth pair Silas Octakiseron and Colum Asht, and the frail, charming Dulcinea Septimus with her formidable cavalier Protesilaus. Harrow and Gideon complete a trial involving a regenerating bone construct by linking Harrow’s necromantic perception to Gideon’s senses, winning a scarlet key and a rare moment of mutual respect. That triumph collapses when they find Abigail and Magnus dead at the bottom of the ladder.
The deaths transform the trial into a crisis. The necromancers fail to call Abigail and Magnus back, and Silas’s attempt to use Colum as a soul siphon nearly empties everyone present, terrifying Teacher. Arguments over keys reveal that the trials have no real law against theft, violence, or coercion. Gideon and Harrow use their key to open a preserved study connected to the trial, discovering Lyctoral theorems about transference and the use of a living soul. Dulcinea then draws them into another trial, Avulsion, where Harrow must drain Gideon’s life energy to cross a lethal field. Gideon agrees and nearly dies, deepening both the danger of the trials and the trust between them.
The situation worsens as Protesilaus disappears, the Fourth House finds suspicious ashes in an incinerator, and duels break out over keys. Camilla defeats Marta when Judith tries to seize the Sixth’s keys, and Gideon, Harrow, and the Fourth intervene to protect the wounded Sixth from the Third’s opportunism. Gideon leads Isaac and Jeannemary below to search for Protesilaus, but an enormous bone construct attacks. Isaac dies fighting it, and Gideon carries Jeannemary to a locked study for safety. When Gideon wakes after a brief sleep, Jeannemary has been murdered by bone spears, proving the killer can strike even behind locked doors.
Grief and suspicion fracture Gideon’s loyalty to Harrow. Dulcinea comforts her and deduces that Gideon is not a properly pledged cavalier. Silas then reveals that Sister Glaurica and Ortus died in a shuttle explosion and suggests the Ninth’s leaders murdered their own children to create Harrow. Gideon later finds Protesilaus’s severed head hidden in Harrow’s room, but Palamedes exposes the truth: the Protesilaus who arrived at Canaan House was already dead, animated by forbidden Seventh House corpse magic. Harrow finally confesses the deeper Ninth secrets to Gideon: her parents killed two hundred children to produce her, Gideon impossibly survived the poison, and Harrow opened the Locked Tomb as a child. The confession transforms their hatred into a chosen bond, and Gideon renews the cavalier vow: one flesh, one end.
Further investigation reveals that Canaan House’s skeleton servants are revenants and that Teacher is a hundred-soul guardian. Judith and Marta send an SOS to the Imperial flagship, but Teacher attacks them trying to stop the message; Marta dies, Judith is mortally wounded, and Teacher warns that the Emperor must not return because one of them has come back. Meanwhile, the Third House cuts open Abigail’s corpse and steals a hidden key. In a hidden laboratory, Ianthe reveals the secret of Lyctorhood: a necromancer ascends by killing, preserving, absorbing, and using the cavalier’s soul. She has murdered Naberius and become a Lyctor, also revealing that Coronabeth was never a necromancer. Silas condemns her, but his soul siphoning opens Colum to possession; Colum kills Silas before Ianthe kills Colum.
Palamedes then uncovers the central deception. The woman posing as Dulcinea is actually Cytherea the First, an ancient Lyctor who murdered the real Dulcinea and Protesilaus before arrival. She killed Abigail and Magnus because Abigail’s historical knowledge and spirit skills threatened her, and she orchestrated the chaos to ruin the Emperor’s Lyctoral plans and lure him back. Palamedes sacrifices himself in a vast thanergy explosion, but Cytherea survives, badly damaged yet still powerful.
Gideon, Harrow, Camilla, and Ianthe make a final stand against Cytherea and her regenerating construct. Harrow develops perpetual bone to trap the monster, Camilla wounds Cytherea, and Ianthe fights as an incomplete Lyctor but is drained and maimed. When all defenses fail, Harrow prepares to sacrifice herself, but Gideon chooses the cavalier’s end instead. She impales herself so Harrow can complete the Lyctoral process. Guided by Gideon’s presence inside her, Harrow gains Gideon’s swordsmanship, destroys the construct, and uses Palamedes’s lingering damage to kill Cytherea.
In the epilogue, Harrow wakes aboard a vessel in space before the Emperor Undying. She begs him to restore Gideon, but he explains that Gideon’s soul is now fused with Harrow’s and removing it would destroy them both. Ianthe is alive, while Camilla, Judith, and Coronabeth are missing, and Gideon’s body has not been recovered. The Emperor says the Empire is dying and asks Harrow to serve as one of his Hands. Grieving, needing answers, and unable to return unchanged, Harrow accepts and is named Harrowhark the First.
Characters
- Gideon NavThe Ninth House ward and swordswoman who longs to escape Drearburh for the Cohort but is forced to become Harrowhark’s replacement cavalier. Her practical fighting skill, loyalty, grief, and final sacrifice drive Harrow’s survival and transformation.
- Harrowhark NonagesimusThe Reverend Daughter of the Ninth, a brilliant necromancer seeking Lyctorhood to save her failing House and preserve the Locked Tomb. Her secrecy and cruelty give way to trust in Gideon, and Gideon’s sacrifice makes her Harrowhark the First.
- AiglameneThe Ninth House sword-master and guard captain who trained Gideon and later prepares her for the role of cavalier. She is one of the few Ninth figures Gideon respects and helps make Gideon’s departure possible.
- CruxThe marshal of Drearburh, fiercely loyal to the Ninth and openly hateful toward Gideon. He enforces Harrow’s authority and is later implied to have caused the shuttle explosion that killed Ortus and Glaurica.
- Ortus NigenadHarrow’s original cavalier, a fearful and inadequate swordsman who flees the Ninth with his mother. His desertion creates the opening for Gideon to become Harrow’s cavalier.
- Sister GlauricaOrtus’s mother, who helps him steal Gideon’s shuttle to escape the Lyctor summons. After her death in the shuttle explosion, her revenant testimony gives Silas information about Gideon and the Ninth.
- Pelleamena and Priamhark NonagesimusHarrowhark’s parents, the former rulers of the Ninth House. They murdered the Ninth’s children to create Harrow, then died by suicide after Harrow opened the Locked Tomb, leaving Harrow to preserve their corpses as puppets.
- Mortus the NinthThe cavalier of Harrow’s parents who died by hanging alongside them after Harrow breached the Locked Tomb. His death is part of the childhood trauma that shaped Gideon and Harrow’s hatred.
- TeacherThe priestly guide of Canaan House who welcomes the candidates while withholding the full danger of the place. He is revealed as a hundred-soul guardian constructed to contain or recognize a returning threat.
- Palamedes SextusThe Sixth House necromancer, investigator, and scholar who pieces together the logic of the Lyctor trials and the murders. His love for the real Dulcinea and his sacrifice against Cytherea make him central to exposing the killer.
- Camilla HectPalamedes’s cavalier, a disciplined and exceptionally dangerous fighter whose loyalty mirrors the ideal cavalier bond. She protects Palamedes, defeats Marta, aids the investigation, and is reported missing after Canaan House.
- Dulcinea SeptimusThe real Seventh House necromancer, fatally ill and summoned to Canaan House, whose identity is stolen before arrival. Her name and history are used by Cytherea to manipulate Gideon, Palamedes, and the other Houses.
- Cytherea the FirstAn ancient Lyctor who impersonates Dulcinea Septimus and orchestrates the murders at Canaan House. She seeks to ruin the Emperor’s plans and lure him back, becoming the final antagonist Gideon and Harrow must face.
- Protesilaus EbdomaThe Seventh House cavalier, killed before Canaan House and animated by forbidden corpse magic. His severed head and burned remains expose the false Dulcinea’s deception.
- Ianthe TridentariusOne of the Third House twins, a cold and ambitious necromancer who solves the secret of Lyctorhood by killing and absorbing Naberius. She survives Canaan House as a maimed new Lyctor.
- Coronabeth TridentariusThe radiant Third House princess, publicly presented as Ianthe’s twin necromancer but revealed to have no necromantic ability. Her dependence on Ianthe and grief over being passed over for Naberius expose the Third House’s central deception.
- Naberius TernThe Third House cavalier, a technically skilled and vain duelist bound to the Tridentarius twins. Ianthe kills and absorbs him to become a Lyctor, gaining his swordsmanship and power.
- Abigail PentThe Fifth House necromancer, historian, and spirit expert whose knowledge makes her dangerous to Cytherea. Her murder with Magnus begins the open crisis at Canaan House, and a hidden key in her body becomes an important clue.
- Magnus QuinnAbigail’s husband and cavalier, a warm and courteous Fifth House figure who treats Gideon kindly. His death alongside Abigail turns the trials from rivalry into murder investigation.
- Isaac TettaresThe young Fourth House necromancer, grieving the Fifth and determined to confront the danger below Canaan House. He dies fighting the enormous bone construct during the search for Protesilaus.
- Jeannemary ChaturThe young Fourth House cavalier, impulsive, brave, and admiring of Gideon’s practical combat style. After Isaac is killed, she is murdered in a locked study, deepening Gideon’s guilt.
- Judith DeuterosThe Second House captain who repeatedly tries to impose Cohort-style order on the collapsing trial. Her SOS brings the Emperor toward Canaan House, and she is later reported missing.
- Marta DyasJudith’s cavalier, a disciplined soldier who duels Camilla and is defeated. She later dies with Judith during the failed attempt to summon help.
- Silas OctakiseronThe Eighth House necromancer, a severe soul siphoner who condemns the Lyctor trials as heretical. His repeated use of Colum as a battery leads to Colum’s possession and Silas’s death.
- Colum AshtSilas’s cavalier and uncle, trained and conditioned to serve as Silas’s siphoning vessel. He shows moral independence by protecting Gideon from Silas, but later becomes possessed after Silas drains him too deeply.
- The Emperor UndyingThe Necromancer Prime and ruler of the Nine Houses, who summons the heirs to seek new Lyctors. After Canaan House, he tells Harrow that Gideon cannot be restored and recruits her as Harrowhark the First.
- The girl in the Locked TombThe frozen chained corpse Harrow saw when she opened the forbidden Tomb as a child. Her face gave Harrow the will to live and remains the sacred secret Harrow asks Gideon to protect.
Themes
Tamsyn Muir’s Gideon the Ninth braids gothic horror, locked-room mystery, and space opera around a set of deeply emotional themes: what people owe one another, what institutions demand from bodies, and whether love can survive systems built on exploitation.
- Bondage, service, and chosen loyalty. Gideon begins as property of the Ninth House, attempting yet another escape from Drearburh’s deathly rituals and Harrow’s control. Yet the book gradually transforms service from coercion into choice. Her forced role as cavalier becomes, through shared trials, a genuine partnership. The phrase “one flesh, one end” first sounds like feudal doctrine, but by the final chapters Gideon makes it intimate and voluntary: not obedience to the Ninth, but devotion to Harrow.
- The horror of sacred institutions. Every House dresses violence in ritual language. The Ninth preserves dead parents, worships the Locked Tomb, and literally sacrifices children to produce Harrow. The Eighth’s soul siphoning reduces Colum to a tool. Canaan House itself, with its revenant servants and hidden laboratories, reveals that Lyctorhood—the Empire’s holiest calling—is founded on consuming another soul. The novel repeatedly asks what “holy” means when holiness requires victims.
- Trust as survival. Canaan House is designed to isolate: locked doors, hidden keys, secret trials, and political suspicion pit the Houses against one another. Abigail and Magnus’s deaths, the Fourth teens’ murder, and Dulcinea/Cytherea’s deception show how secrecy kills. Gideon and Harrow only become effective when they stop working separately: the Response trial, the construct battle, and the final confrontation all depend on shared perception and vulnerability.
- Identity, performance, and masks. Nearly everyone performs a role. Gideon impersonates a proper Ninth cavalier; Harrow puppets her parents; Coronabeth pretends to be a necromancer; Cytherea wears Dulcinea’s life; Ianthe becomes a Lyctor by absorbing Naberius. Face paint, robes, titles, and bodies themselves become costumes. The plot’s revelations strip these masks away, exposing grief, ambition, shame, and hunger beneath.
- Love entangled with death. The novel’s central relationships are necromantic in more than genre. Harrow is born from mass death; Palamedes destroys himself for Dulcinea’s memory; Gideon gives her life so Harrow can live. Muir makes sacrifice both beautiful and horrifying, leaving readers with the painful question the epilogue sharpens: if love means carrying another soul forever, is that salvation, damnation, or both?