Bryce’s plan works: she has been reopening wounds and smearing her blood to lure the Middengard Wyrm to her, intending to use the attack as cover to slip away from Nesta and Azriel and find what Urd sent her to discover. When the Wyrm attacks, Bryce bolts down the tunnel, leaving Nesta and Azriel to fight. After hearing their pained shouts and realizing what she has done mirrors the Fae brutality carved on the walls, Bryce turns back, hoping she has not doomed them.

Bryce finds the riverbank empty and panics when she spots Nesta apparently sprawled on a rock, only for it to be a trap: Nesta is unharmed, and Azriel has Bryce at knifepoint for abandoning them. They explain the Wyrm uses deep sinkholes in the riverbed to vanish and stalk, then decide to use Bryce as bait because her blood trail drew it in. The Wyrm erupts repeatedly from different sinkholes; Azriel’s blue light and Nesta’s silver fire strike it, but the creature absorbs their power, forcing them to reassess.

Nesta refuses to let the Wyrm live, and Azriel lifts all three into the air with his wings to avoid a killing lunge. They debate options: Azriel cannot hold it with his tethers, and Bryce offers to take the Starsword to try to kill it. Instead, Nesta reveals a metallic Mask and puts it on despite Azriel’s alarm, unleashing a death-chill presence and a voice in Bryce’s mind repeating a mortal warning.

As the Wyrm surges into the tunnel again, Nesta uses the Mask to reanimate the massive skeleton they previously encountered. The bone creature grapples the Wyrm, pins it, and holds it down under Nesta’s command while the cavern shakes with impacts and falling debris. Using the opening, Nesta climbs the undead creature and drives Ataraxia into the Wyrm’s head, sending a rush of silver fire through it; the Wyrm collapses dead, and the silence afterward feels worse than the battle.

Azriel rushes to Nesta and demands she remove the Mask and let the undead creature rest. Nesta’s movements remain unnervingly inhuman until Azriel anchors her by invoking Cassian, the House of Wind, and their friends—Gwyn, Emerie, Feyre, Elain, and especially Nyx—until the Mask’s influence breaks. The Mask falls away, the undead bones collapse, and Nesta steadies herself, dismisses the Mask, and orders Bryce to keep walking.

On Midgard, Ithan returns from the Viper Queen and tells Tharion, Declan, Flynn, Sigrid, and Ketos that the price for safe passage and Ketos’s freedom is one private arena fight from Ithan tomorrow night. Tharion erupts, insisting Ithan should not trust the Viper Queen and that Tharion cannot truly leave because the River Queen would reclaim him, then storms out. Marc is allowed to leave to pursue a legal route anyway, while Flynn presses whiskey on Ithan, warning the Viper Queen will choose an opponent meant to break him.