Simon escorts Helena through the second circle and explains the Chain's version of history: Draxus Cale was abandoned by his companions, rewarded the lineages that offered him fealty, and subjugated those who opposed him. He also reveals that citizens who willingly become Rusticulum elevate their families and that Draxus intends to carry his order beyond Tyve. Meanwhile, the Lion and a new Raven offer the other Harbingers golden rings containing Draxus's own will, which can protect them from the Chain's commands, and agree to guide them toward the inner circle through hidden tunnels. Simon captures Lefty and Lynx, kills Lefty by breaking his ring and stopping his breath, and forces Lynx to lead him toward the resistance. Helena secretly warns Torin through Sending, allowing the Harbingers to flee moments before Simon reaches the Chunky Link and Ike is killed. The group enters the resistance's underground refuge, uses an ancient portal at Ostia to send Bjork back to Keph, and escapes with the Lion and Raven while a pursuing Rusticulum tears through the defenses behind them.
The Lion leads the Harbingers beneath the second circle, where Rhino and the Ant guard the resistance's farthest outpost. When the group climbs into the city, the completed portion of the Crystallic floods Torrin with visions of fire as dragons descend upon the Chained Fortress. Helena is taken back to the Panopticon, where Draxus shatters her will after declaring that he cares only about using Whisper and Ernan to open the Dios Ostium. The Harbingers race through the panicked second circle until Draxus notices them and turns from the dragon attack to pursue them. Vyr activates Mathias Ephelthine's anchor ring, but it carries her to Horatio Vinvestler's true fortress instead. A recovered vision reveals that Draxus, Mathias, Angela Thedon, Aran Melosis, Andrix, and Horatio once invaded Traeus and freed two white beings that imitated Draxus and Angela before calling Draxus their father. Zyltrix intervened, killed Andrix, transported the surviving intruders and the beings onto a ship, and forced them toward Tyve to complete the mission they had disrupted. In the present, Horatio tells Vyr that one of the brothers must be sacrificed, gives her a wand capable of breaching the final wall, and sends her back. He later restores enough of Helena's broken mind to make her useful, kills Simon, implants an unknown secret within her, and sends her after the others.
Vyr's wand releases an expanding sphere of annihilation that consumes a vast section of the third wall, allowing the reunited Harbingers to enter the blood-soaked inner circle beneath the Dios Ostium. Ernan's key opens a waiting box containing the final Crystallic fragment, and Torrin completes the artifact. The restored Crystallic offers him a permanent choice between preserving its power and returning Kypheron to sleep, but he initially keeps it available so the party can reach the Ithelion. Wylas Velpa appears holding an injured Lily hostage, but Torrin banishes him into the Evenfall and Whisper rescues her. Ernan then allows the sacrificial chains to bind him, intending to open the door and prevent Kypheron's awakening. Helena refuses to let him die alone, cuts open the sun marking upon her arm, and takes the chains beside him. The Dios Ostium opens without the Crystallic, releases them both, and a voice that Torrin recognizes as Valens Avarith welcomes him home. The Harbingers behold the distant Ithelion before a storm of living darkness erupts from Tyve's heart and obscures it. With Draxus and the citizens of the Chain closing in, Torrin finally uses the Crystallic to return Kypheron to sleep, causing the attacking dragons to fall from the sky. The Harbingers carry Lily through the Dios Ostium, cross a lightless expanse together, and emerge from the sea upon an unfamiliar shore with Iftalus to the northeast and the Triune Mountains of Scarston to the northwest.