In an ancient memory, Torin stands beside Valence Avorinth as the Vey lose their war against the Teller. Black obelisk machines fire into the Ithelion, tearing a single shard from the living light at the cost of years of work and beginning a decline that may take millennia. Valence entrusts the shard to Torin, who later gives it to his daughter on the shore of the Sequestered Sea and sends her north toward Tarath to find Tilda and seek help. As the Ithelion's radiance withdraws and Tyve's stars disappear behind clouds, Torin blesses the departing girl. His grieving partner then embraces him and drives a blade into his back, apologizing that his death was the price of their daughter's safety.

In the present, the company hides inside Gavra's way-gate chamber as masked priests and two guards bring Ellie, a drugged young seamstress, to be purified. The gate opens a route called Shalyle, and a beam begins pulling the darkness from her. Bjorn pushes Ellie free and takes the beam himself, Whisper attacks one priest, and Torin stops the rite by naming Shalyle. After Ellie recovers, the group accepts arrest and meets Marquis Selendra Cassiandros. She claims ignorance of the secret sacrifices and asks the companions to help stop a political insurrection. Normandy's Velpan records give her leverage against Wylas Velpa, but she still needs proof against the Felrick family or unequivocal support from two other houses. She gives the group a brooch for discreet access, eight writs of passage, and four hundred gold. Selendra also reveals that Silas has taken a small army north toward the mainland after blaming the Chain for the returning plague.

The investigators buy potions, an armor upgrade, explosives, and disguise materials while tracing the Felricks and Yore and Gander. At a Black Worm shop, Torin experiences a vision of Ephthalas's sealed door, souls held between life and death, a bleeding tree of golden light, and a command to enter through darkness and restore the Ithelion. The worm's keeper calls himself Ilk and says his acolytes serve a greater purpose. Gossip then leads the group to Kyle, a former Arcanium member who confirms that Yore and Gander's ouroboros is also the Arcanium's symbol and that the order tried to purify dark winds. Before that meeting, Charlie admits that his glister comes from the Felricks and gives the party two portions on credit, creating a five-hundred-gold obligation due in twenty-four hours. The Assassin's Guild separately grants Whisper a seventy-two-hour reprieve. As the company plans to watch Charlie's operation, Lily's Song drifts days away with its mast collapsed and everyone aboard unconscious, until Aggie opens her eyes.