Bryce Quinlan’s routine at Griffin Antiquities ruptures when her best friend, wolf alpha Danika Fendyr, and the Pack of Devils are slaughtered by an eyeless demon after a citywide power outage. Bryce staggers onto the scene in time to drive the creature off and save a dying angel, but the shock is weaponized against her when the 33rd Legion interrogates her and plays audio of Danika’s final moments. Philip Briggs, a human rebel bomb-maker Danika once arrested, is blamed, but the case soon stalls. Bryce refuses Danika’s public rites, kneeling instead at the Bone Quarter’s gates in private grief.

Twenty-two months later, a new murder—vampyr Maximus Tertian—matches the pack’s wounds. Archangel Governor Micah Domitus conscripts Bryce to investigate and assigns his enslaved assassin, Hunt Athalar, as her protector. The reopened inquiry digs into two threads: the theft of Luna’s Horn, a sacred Fae artifact stolen the night of the blackout, and the kristallos, a demon bred to hunt the Horn. Bryce and Hunt test leads in the Meat Market, confront the Viper Queen, and find she’s uninvolved but points them toward painful places. Working in Jesiba Roga’s outlaw archive beneath the gallery, they piece together how the Horn once worked through Starborn power and why a kristallos would be prowling Lunathion.

New killings along ley-line avenues suggest a summoner with insider knowledge. Bryce and Hunt clash with wolves in Moonwood; Sabine Fendyr lies about Danika’s whereabouts during the Horn theft, and later admits Danika herself stole the Horn. Another thread emerges when a dangerous drug, synth—synthetic magic laced with obsidian salt—surfaces on victims’ clothing. The drug can supercharge humans and, in heavy doses, open rifts and summon demons. Danika is seen moving a crate of synth by boat before her death, and Bryce learns Danika hid the drug from her to protect her. The White Raven nightclub is bombed by human rebels, and Bryce saves her friend Juniper while realizing the case and city are entangled.

Micah privately bargains with Hunt: solve the murders before the Summit and his 2,217-kill debt will drop to ten. As Bryce and Hunt grow closer, a barge sting explodes the fragile trust—Micah uses the Viper Queen to expose a synth buy by Hunt, Viktoria, and Justinian meant to fuel rebellion. Hunt claims he moved to stop the deal after seeing synth’s carnage, but Micah arrests them all. Justinian is crucified; Viktoria is caged in glass; Hunt awaits a worse fate. At the Summit in the Psamathe Desert, power players assemble: the Autumn King, Sabine, the River Court, the witches led by newly anointed Queen Hypaxia Enador, and Sandriel—Hunt’s former master.

With most forces out of the city, Micah visits the gallery library—secretly the lost human archive of Parthos—and reveals his design. Danika stole the Horn and had its ground powder inked into a tattoo on Bryce’s back; Micah orchestrated the synth crisis, demon attacks, and bombings to repair and claim the Horn. He injects Bryce with synth to “heal” it and tries to activate the tattoo. Bryce uses Parthos books to force him into a bathroom; when Micah throws her chimera Syrinx into a nøkk tank, Bryce hyperventilates, dives, and saves him. Lehabah, the fire sprite guarding the archives, chooses freedom and sacrifice, shattering the tank to flood the library and buy Bryce time.

Riding the synth’s edge, Bryce assembles Jesiba’s Godslayer Rifle, opens the front door as a decoy, and executes Micah with a golden “Memento Mori” round, then dismembers and burns him with Danika’s sword. The victory curdles when the city’s seven Gates ignite into black rifts: Micah’s attempt to use the Horn worked after all. Demons pour into Lunathion. As Aux leaders hide behind protocol, Bryce straps on Hunt’s weapons and Danika’s jacket, fights block by block, and calls civilians to shelters. The Viper Queen’s fighters and wolves led by Ithan Holstrom join her to secure an Asphodel Meadows shelter; Bryce shoves Ithan inside as doors slam citywide, then runs alone toward the Old Square Heart Gate.

At the Summit, Sandriel tips off the Asteri about Bryce’s potential; Hypaxia quietly dissolves Hunt’s halo, freeing him. Hunt kills Sandriel in a lightning strike, seizes command, and lifts with allies toward the city aboard Fury Axtar’s helicopter. When Asterian Guard tanks begin bombarding Lunathion with brimstone, Hunt jumps without hesitation, shields Bryce with his body and lightning, and is torn apart by the blast.

Facing a dying Hunt and a city failing, Bryce chooses an impossible gambit. She places her hand on the Heart Gate’s plaque and initiates an untethered Drop, willing the Gate’s store of citizen-offered power to fuel her descent and the Horn within her to seal the rifts. Across the city, Gates blaze and the ley lines ignite; portals to Hel pinch shut; streets and bodies mend. Bryce’s power surpasses Ruhn’s and edges past the Autumn King’s, but her heart flatlines—she has no living Anchor.

In the liminal deep, Bryce clings to Danika’s lingering spark, wanting to stay. Danika urges her on—reminding her of Ember and Randall, of friends, and of Hunt now healing—then spends her last strength to push Bryce into the Ascent. On the stones of Old Square, Hunt shocks Bryce’s heart; she returns, alive, lightning wreathed in his wings.

Afterward, Asteri leader Rigelus calls to “thank” Bryce, frees Hunt, and threatens them into silence: live quietly and never use the Horn. Bryce reconciles with Ruhn, now openly her Starborn brother, and claims found family among witches, mer, wolves, and friends who chose to stand with her. In the epilogue, Jesiba confronts Aidas, Prince of the Chasm, who confirms Bryce bears Theia’s ancient light and hints that greater forces are moving, even as the library of Parthos is spirited away to safety.