In the city of Lumen, the sun is a myth. The only light comes from the dead.

Maren is a Chandler. In a world trapped in eternal night, she works the "Rendering Vats," boiling down the bodies of the aristocracy to create the golden "Soul-Candles" that light the palaces of the elite. She is numb, covered in burns, and smells permanently of grease and smoke. To her, a human body is not a vessel of the soul; it is fuel.

Kade is a Snuffer. An elite assassin for the Church, his duty is to "extinguish" those who have lived too long or become corrupt. He wields a blade that doesn't cut flesh but cauterizes the soul, leaving no ghosts behind. He is a creature of the dark, terrified of the shadows he creates, yet addicted to the light he destroys.

The dynamic is simple: Kade brings the bodies; Maren renders the fat. But in a freezing city, Maren is the only source of warmth Kade has ever known.

As the fires of the vats roar, a forbidden attraction ignites between the woman who makes the light and the man who ends it. But when Maren discovers that the "Saintly Dead" are being boiled alive to make the candles burn brighter, she realizes the entire city is powered by torture.

Now, she must make a choice: continue feeding the vats to keep the darkness at bay, or let the city freeze to save her soul. And Kade, the man sworn to extinguish the corrupt, must decide if he can kill the only woman who ever made him feel warm.

She is the wick. He is the flame. Together, they will burn the world down.