Dawn (Warriors: The New Prophecy #3) by Erin Hunter

DARKNESS, AIR, WATER, AND SKY WILL SHAKE THE FOREST TO ITS ROOTS.

The young cats who set off on a quest many moons ago have returned with a chilling message: the Clans must move to a new home, or risk destruction. But the cats have no idea where to go. What they need is a sign from StarClan . . .