Dragonquest is the story of how all factions on a tradition-bound planet rally together to find a more permanent solution to a deadly menace than the valiant battle waged by fire breathing dragons and their heroic riders.

The planet Pern is menaced not only by Thread, a dreaded infiltration from space that burns flora and fauna, but also by friction among the ruling Lord Holders and between stodgy Oldtime dragonmen and current progressives led by F'lar of Benden Weyr. F'lar is a moderate reformer. Short-tempered T'bor is his only ally. Dragons transport themselves and their riders across space instantaneously -a bone-chilling experience called "bursting out of between" - and communicate telepathically among themselves and with the riders to whom they are "Impressed." Currently the defense against Threadfall calls for dragons char it mid-air and human ground crews to be sure none has gotten through and burrowed into the soil. F'lar knows there must be more effective ways.

F'lar's half-brother, F'nor, is wounded in an attack by dragonriders and nursed at Southern by the dragonrider Brekke, assistant to the nasty, seductive Weyrwoman Kylara. Brekke is able to talk to dragons besides her Wirenth. F'nor discovers a nest of fire lizard hatchlings, and he, Brekke, and her fosterling Mirrim rescue and Impress a few. The leaders consider whether commoners keeping them as pets might not experience the unique love that dragons give and receive. By accident, they happen upon ancient scientific equipment that gives hope of ending the scourge of Thread. Kylara goes into the dragon business to get revenge on anyone who has ever wronged her.

A number of events converge: a "distance-writer" (telegraph) is invented, providing quick communications across Pern. Off-schedule Threadfall in the Southern Weyr reveals grubs that seem to protect vegetation; this is proven experimentally at Benden Weyr. Showing off her lizard, Kylara sows enmity among the Lord Holders at a gala wedding, where all the various options for fighting Thread come together and compete. Threadfall galvanizes everyone except T'ron, who picks a fight with F'lar, wounds him gravely, but is defeated, leading to the Oldtimers' exile and a chance for the North to embrace F'lar's big picture. Still, it remains a hard sell. Some demand an expedition to the Red Star, but this is impossible without in-depth and interdisciplinary study and cooperation across jurisdictions

Kylara alienates her Prideth, who goes into heat at the same time as Brekke's Wirenth, resulting in the tragic death of two queens. Brekke becomes suicidally depressed and F'nor drops all else to attend to her. The Lord Holders take turns observing the Red Star through an ancient "distance-viewer" (telescope) and hope it can provide the data by brave dragonriders to invade. Queen Ramoth's eggs hatch, and the underaged Lord Jaxom Impresses one, inspiring his fellow nobles argue about what to do. Finally, there are calls for eliminating passé customs. It is discovered that farmers for generations have been exterminating grubs as pests, thus preventing Pern from becoming immune.

To keep his invaluable half-brother from taking the risk, F'nor and Canth go between to the Red Star, where they nearly perish in a broiling maelstrom. In the end, unromantic grubs are recognized as Pern's salvation, but the romantic dragons and their riders are destined to shine on.