Dorian secretly follows Celaena into the hidden passages beneath the library after noticing that she is armed and wearing her hair for a fight. His own magic warns him to leave, but concern for Celaena drives him deeper into the catacombs, where he finds marked iron doors and descends after her.

Meanwhile, Celaena flees the obsidian base of the clock tower, shaken by the implication that the king’s forbidden black stone may be connected to the Wyrdkeys. In the darkness, the Eye of Elena begins to glow, and a warped, once-human creature stalks her. The creature has survived in the dungeon, learned Wyrdmarks, and believes Celaena is tied to the people who tortured and remade it.

The creature attacks, and Celaena wounds it but cannot stop it. She realizes the iron doors were meant to contain it and that by breaking the spells on them she has freed it. Dorian hears the fight, and Celaena warns him to run; the two retreat together through the passages, repeatedly slamming iron doors between themselves and the monster.

At the final door, the creature nearly breaks through. Dorian’s hidden magic erupts as he instinctively tries to weld the iron shut, confirming Celaena’s suspicion that he has power despite the king’s ban on magic. When Dorian cannot hold the seal, he cuts off the creature’s hand with Damaris, giving Celaena time to send him for The Walking Dead.

Dorian retrieves the book, and Celaena uses her own blood to draw a binding spell around the threshold. When they open the door, the spell freezes the creature in place long enough for Celaena to behead and dismember it. She then seals the door again, and both agree that telling anyone, even Chaol, would expose dangerous secrets about Celaena’s Wyrdmark work and Dorian’s magic.

In Dorian’s rooms, Celaena explains only part of what she has learned, withholding her suspicion that the king used a Wyrdkey to create the creature and perhaps others. Dorian admits his magic first surfaced in anger and that he has been searching noble genealogies for an explanation. Celaena promises not to betray him, recalling loved ones executed for magic, and they decide to watch the sealed door, seek healing, and handle the danger day by day.