For over a thousand years, Queen Servilia has ruled the world of Illium. Using magical red dust mined from the earth, she has enslaved her subjects, enforcing uniformity and sameness to maintain her absolute power. But in Village Twenty-One, wild magic is growing. Fen, a young girl whose hand has been cut off as punishment for theft, wakes one morning to discover that her hair has gone crimson: a sign that she has been invested with magic of her own, and is a threat to Servilia's reign. For Fen, this is a death sentence. When her village is burned to the ground and her sister captured, Fen must make an impossible choice. Will she risk unleashing the most feared magical entity of all time — an ancient god who could overthrow Servilia, but whose power may be even more terrifying — in order to save the only family she has left?