The Slave City of Khul, a proud Kingdom founded by slaves, is invaded. The Slave King and his family slaughtered and resistance brutally suppressed. The former slaves are slaves once more. The slaves whisper a name that has not been heard or repeated since the City fell. Avtar. Avtar is their king. Thirteen year-old Watt is a Ghosty Boy, so called for the flour-covered uniform of The Baker's apprentices, and works in the ancient fortress of Slave City, a far- flung outreach of Empire. When Watt gets stuck cleaning the Baker's chimney, he falls into a labyrinth of corridors where he finds his sister, Melior, and his life is turned upside down.

All Watt wants to do is survive, but Melior dreams of sweet revenge.