Mathias Ephelthine drains Normandy's life, but the Deathless Flame refuses to let his soul leave. Normandy rises in a skeletal dread form wreathed in chartreuse fire and speaking with many voices, while the former bearer fades into dust and the dead depth crawler awakens under Normandy's command. When Vyr tries to recover Mathias's fallen book, it seizes her mind and turns her blade against the group. Normandy strikes the book with flame, freeing Vyr and disintegrating it as a scream tears through every mind in the chamber. Still uncertain whether Mathias is dead, the Harbingers explore the buried stronghold with their undead monster, recover old Dragdah armor, and descend into catacombs filled with hundreds of lightless.

At the center of the catacombs, a concealed Veyan tableau depicts Valence Avorinth between two Vey, one turned toward shadow and one proudly facing the light, with a Crystallic fragment sealed inside an orb. Torrin, Bjorn, and Vyr operate the three figures together, breaking the seal and freezing the attacking lightless long enough to claim the shard. Normandy commands the overwhelmed depth crawler to release its power, and the creature erupts in chartreuse fire that destroys much of the catacombs. Within the flames, the party witnesses Emrys Valakar sacrifice his life to ignite a soul forge and sees flashes of three flame-bound lives, with Normandy's own counted as the fourth. A hidden array of plinths then draws away most of Normandy's fire, leaving him young but deathly pale, and releases a wave of power that melts and collapses the glacier surrounding Dragdah. A one-way passage carries the Harbingers beneath Tch'nev, where they find the Tome of Stars beside Angelos's freshly burned corpse.

The group conceals Normandy's transformation and claims that he sacrificed himself, even as the glacier's collapse threatens Eilinor with debris and flooding. Calem del Mortez initially refuses to let the Grey Knights abandon Tch'nev because of their inherited oath, while Elos suspects the Harbingers were involved in Angelos's death. Vyr persuades Calem to consider entrusting them with the Tome of Stars so they can attempt to destroy it beyond the Dio Ostium. Cass demands that the Harbingers become honest heroes before expecting the order to follow them. The next morning, Calem convenes the Grey Knights and asks whether the group will protect the oath and whether they truly believe they can open the sealed gate. After hearing their answers, Calem invokes the order's sacred law, takes every knight's punishment upon himself, and is killed by four captains. Declaring this freedom to be Elos's legacy, he ends the oath. The captains entrust his helmet to the Harbingers as the helm of the Oathbreaker, and the Grey Knights choose to stand with the Harbingers of Light.