When AIVAS -- the Artificial Intelligence Voice Address System -- was first discovered at Landing the enture planet of Pern was awed at the knowledge it divulged. All the history of the people of Pern was there. Dragonholders Lord Holders & Craftmasters crowded into the tiny inner room to learn the secrets of their beginnings. Ana AIVAS had other gifts to offer -- stored information of old crafts that had been forgotten of medicine music & technology. Bu the greatest promise AIVAS offered was the chance to rid Pern of Thread forever. All the great ones of Pern began the long & arduous task of learning just how to operate the incredible plan -- a plan of such daring & epic proportions that both dragons & riders would be put at risk.