Gideon, Harrow, Palamedes, Camilla, Silas, and Colum move through Canaan House after the skeletal servants have collapsed. Following Harrow's map, they open another Lyctoral door and enter a strangely beautiful laboratory marked by the words YOU LIED TO US. Inside, Coronabeth is sobbing, Naberius Tern lies dead, and Ianthe waits blood-spattered and unstable.

Ianthe announces that she killed Naberius, then corrects the implication: she has absorbed him. Ianthe explains that she reverse-engineered the Lyctoral process without collecting the keys, recognizing that the trials were meant to teach preservation, absorption, incorporation, and use of a cavalier's soul. The revelation makes clear that Lyctorhood depends on the necromancer consuming the cavalier's soul and using that power forever.

Ianthe also exposes the Third House's central lie: Coronabeth is not a necromancer. Their family wanted matched heirs, so Ianthe has pretended to be two necromancers since childhood. Palamedes is horrified by the obviousness and brutality of the solution, while Silas interprets Lyctorhood as a heresy against the sacred compact between necromancer, cavalier, and Emperor.

Silas condemns Ianthe to death and orders Colum to attack. Ianthe fights with Naberius's precise swordsmanship in her own body, proving that Naberius's skill now lives inside her, though she struggles to sustain it. When Colum gains an advantage, Ianthe shields herself with grotesque flesh magic; Silas then begins siphoning Colum's strength to fight her as a necromancer, despite Colum begging not to be put under.

The fight escalates as Silas drains Ianthe and Colum simultaneously. Ianthe endures, regenerates, and warns that Silas has gone too far. Colum becomes possessed by something inhuman, his body moving unnaturally and his eyes turning black; Harrow's bone spikes fail to hold him, and Silas's commands cannot call him back. The possessed Colum drives a sword through Silas's throat.

Gideon attacks the thing wearing Colum's body, but it overpowers her and nearly strangles her with a monstrous tongue. Ianthe intervenes, snaps Colum's neck, and releases the body back into death. After warning Gideon, Camilla, and Harrow that there are worse things than Ianthe in the building, Ianthe disappears, leaving Naberius, Silas, and Colum dead. Coronabeth clings to Gideon, grieving less clearly for Naberius than for the fact that Ianthe chose to take him instead of Coronabeth.