This 1991 entry into the long running series begins with the rediscovery of the computer left by the first settlers to Pern. This computer, named AIVAS, complete with its vast store of knowledge, had managed to stay operational in the intervening 2,500 plus years since the settlers had been forced to flee the original settlement. In that time the settlers had developed a new society and found methods to deal with the menacing Thread that periodically attacked their world but had lost many of the technologies that their ancestors had brought with them from Earth. Now that AIVAS was available to them the people of Pern would have the opportunity to regain this knowledge, but at what cost to their society?
Favorite characters from previous novels are here, Jaxom and his white dragon Ruth, Master Harper Robinthon, dragonriders Lessa, F'Lar and their son F'lessan and numerous others. We see how the people and dragons of Pern adapt to the changes in their world and rise to met the challenges these changes have brought about.
For long time fans of the series there is a fear that this is the end of the saga but it appears that there are other entries writen more recently. In any case this is a must read for any fan of the series. It is not, however, a good place to start.