The specter of sickness looms over the Weyrs of Pern, felling
fire-lizards and threatening their dragon cousins, Pern's sole defense
against the deadly phenomenon that is Thread. Fiona, the young rider of
queen dragon Talenth, is about to assume the duties of a Weyrwoman when
word spreads that dragons have begun succumbing to the new contagion. As
more dragons sicken and die, Weyrleader B'Nik and queen rider Lorana
comb Fort Weyr's archives in a desperate search for clues from the past
that may hold the solution to the plague. But could the past itself
prove the pathway to salvation for Pern's imperiled dragons? Guided by a
mysterious ally from a wholly unexpected place, and trusting in the
dragon gift for transcending time, Fiona will join a risky expedition
with far-reaching consequences for both Pern's future and her personal
destiny.