I have been reading some of Anne McCaffrey's Pern stories. The world of Pern is underattack by threads. The only defense against the threads are the flying dragons, and the riders who risk all to protect the world.

Dragonflight	For many years there have been no thread attacks, and the world has grown complaicent. Now a Golden Queen is to be born and a female rider is needed. The Riders go to collect the candidates and find Lessa.
DragonQuest	The Threads are falling in earnest now and F'nor must find a way to better protect his world from the falls that are coming faster and closer together. They don't have enough dragons and they don't have nearly enough riders.