In a world of endless dusk, a single spark can set the sky alight.

One found the spark. The other knows how to light it. Both are being hunted. In the vertical ruins of a sunless world, Jace is a scavenger who just found the ultimate prize: a humming black sphere that shouldn't exist. To decode it, he needs Serafina—a brilliant, reclusive mind hidden in the city’s depths. But their discovery has ignited more than just hope. It has sparked a revolution. As the ruthless Harvesters and their terrifying leader, The Crow, close in, Jace and Serafina must race toward the legendary City of Light. In the shadow of the Great Collapse, they are about to learn that the only thing more dangerous than the darkness is the truth behind the light.