Erasmas - Raz - is a young avout living in the Concent, a sanctuary for mathematicians, scientists and philosophers, protected from the corrupting influences of the outside world by ancient stone, honoured traditions and complex rituals. Three times during history's darkest epochs, the cloistered community has been devastated by violence. Yet the avout have always managed to adapt in the wake of catastrophe.
Now, in celebration of the week-long, once-in-a-decade rite, the avout prepare to open the concent's gates. Before the week is out, both worlds - the inner and the outer - will stand poised on the brink of cataclysmic change. Suddenly Erasmas finds himself a major player in a drama that will determine the future of his world - as he sets out on an extraordinary odyssey that will carry him to the most dangerous, inhospitable corners of the plant . . . and beyond.