Shortly after Fiona's return to Fort Weyr, three Turns older and wiser, her queen, Talenth, is infected with the dreaded sickness that has consumed so many of Pern's fire-breathing dragons. Talenth's recovery and the recovery of all the other dragons of Pern is delivered by the efforts of Lorana and Kindan at Benden Weyr.

When Masterharper Zist takes over as Harper for Natalon's coal-mining camp, he takes with him his apprentice, the orphaned Pellar, and Pellar's fire-lizard Chitter. Pellar has become a gifted tracker and Zist gives him his own mission - to find out if the thefts of coal are the work of the criminals condemned to a life of wandering and hardship.

Kindan is an apprentice harper at the Harper Hall but he is finding the lessons very difficult & although he has his friends, Nonala, Kelsa & Verilan, he also has enemies, such as the bully Vaxoram. Things begin to improve for Kindan when he beats Vaxoram in a duel & Vaxoram becomes first his servant & then gradually his friend.

Although Lorana cured the dragons' sickness so many died from the disease that there are no longer enough dragons to fight the deadly Thread, and more dragons and their riders die each Threadfall. With their numbers dwindling, Lorana made the decision to fly forward in time in a desperate bid to bring dragons from the future to fight Thread.

After a vicious plague swept through the world of Pern, there are no longer enough dragons to fight off the current onslaught of Thread, the deadly spore that falls like rain from the skies and devours everything organic in its path.