A sky built on blood. A queen built on lies. A thief who will burn it all down. For ten years, Vespera Thorne has ruled as the High Arbitress of the Obsidian Spire, the cold, masked heart of a city suspended miles above a dying world. To the masses, she is the Law. To the desperate, she is the Savior. But Vespera’s divinity is a calculated lie; her empire stays afloat not on magic, but on the agonizing harvest of stolen souls. When the Spire begins a violent descent toward the earth, the masquerade shatters. To survive the wreckage, Vespera must shed her mask and form a visceral alliance with her greatest enemy: Lyra, a lethal shadow-thief who treats the abyss like a lover and the Arbitress like a target. Amidst the ancient forests of the mainland and the threat of predatory Steam-Lords, a dark, obsessive bond begins to forge between the queen and the thief—a devotion born of blood and jagged necessity. But the abyss they fled is not finished with them. It has followed them into the light, hungry for the Thorne blood that once served as its cage. Vespera has sacrificed her crown and her identity to find the sun, only to face a final, devastating betrayal. As a terrifying shadow rises from the glass forest, she realizes the abyss didn't just want her blood; it wanted a host. Looking into Lyra’s eyes, Vespera sees a hollow void where her lover used to be. She may have saved the world, but the cost is the only soul worth living for.