AIVAS, the Artificial Intelligence Voice Address System that was a part of the original colonists' settlement, is unearthed on the Southern continent after having been buried for generations. This latest volume in the Pern saga deals with the reactions of the various lords, dragonriders, and craftsmen as they realize the impact the artificial intelligence will have on their culture and traditions. With its help, F'lar, Robinton, Lessa, Menolly, and all of the other characters YAs have come to care about devise a risky plan to eliminate a serious threat to their environment.