The Great God Om wakes up to discover he's been incarnated as a tortoise. His church is one of the most powerful on the Disc, but almost nobody actually believes in him anymore - they believe in the church, its hierarchy, and its Inquisition. The only true believer is Brutha, a simple novice with a perfect memory. Together, god and believer must survive the machinations of a theocratic empire. The most self-contained and perhaps the most profound Discworld novel - a book about belief, doubt, and the difference between religion and faith.