For Khadija, the only escape from her arranged betrothal is the sky. When she spots a rogue hot air balloon fighting against its ropes, she leaps at the chance for adventure. She soon finds an unlikely ally in a poor glass-maker's apprentice, Jacob. But Jacob is a hari, and Khadija a Ghadaean. The hari are oppressed and restless, and the ruling Ghadaeans brutal in their repression. The Hareef use forbidden magic, summoning jinn - wicked spirits made of fire - to enact their revenge, forcing Jacob and Khadija to choose what kind of a world they want to save . . .