The second segment (called Dragonrider) received a Nebula Award in 1968.
Dragons are telepathic; each bonds to a single human being when first hatched. They come in various colors which are generally correlated with their size, blue, green, brown, bronze, and gold queens. Bronzes, as the largest males, are by tradition the only ones who compete to win the queens in their mating flights. Queens, however, are always the largest dragons. As their human counterparts are linked mind-to-mind, the humans mate when their dragons mate.
Dragonflight chronicles the story of Lessa, the sole survivor of the noble ruling family of Ruatha Hold on the northern continent of Pern. When the rest of her family was killed by a cruel usurper, Fax, she survived by disguising herself as a drudge (a menial servant).
F'lar, wingleader at Benden Weyr and rider of the bronze dragon Mnementh, finds Lessa while Searching for candidates to Impress the Queen egg which is about to hatch. After defeating Fax in single combat (following the rules of the Pernese code duello), F'lar convinces Lessa to give up her birthright as Lord Holder of Ruatha Hold and join him at Benden Weyr. Lessa Impresses the Queen dragonet Ramoth and becomes the Weyrwoman, the new co-leader of the last active Weyr. On Ramoth's first mating flight, Mnementh catches her, and by Weyr tradition, this makes F'lar the Weyrleader.
Lessa and F'lar warn a dangerously unprepared Pern of the impending Thread reappearance. The general response is disbelief, as the last threadfall was 400 years ago, and the stories about threadfall have receded from recent history into legend and myth. It is not until the first Thread begins to fall that they are believed by the general populace and indeed even by some dragonriders.
One Weyr by itself is not enough to defend the planet; there used to be six, but the other five Weyrs have been empty and abandoned since the last Pass. In a desperate attempt to increase their numbers, a new queen, Prideth, and her rider, Kylara, are sent between times (a recently rediscovered skill), back ten turns, giving Prideth time to mature and have Clutches. Stretched to the breaking point, Lessa travels four hundred turns into the past to bring the five 'missing' Weyrs forward to her present. This not only provides much needed skilled reinforcements in the battle against Thread, but explains how and why the five Weyrs were abandoned: they came forward in time.