Simon and Brad face their greatest danger yet--and discover the secret of the fireball--in the third book of the alternative history Fireball Trilogy, from critically acclaimed Tripods author John Christopher. When Simon and Brad were caught in the mysterious fireball--a whirling ball of light that sucked them into a bizarre alternate world--they knew a terrifyingly different future was ahead. The world on the other side was geographically identical to their own, but the societies and history were completely new...and full of danger. Discovering a pagoda in California was strange enough, but when Simon and Brad are captured by slavers headed to China, the future seems even more hazardous. Especially when they are banished to a remote mountain retreat with the mysteriously powerful Bei-Kun...and come face-to-face with the secret of the fireball.