Something terrifying is happening in the world of the Clans. Amid the destruction of the forest, cats are disappearing, including ThunderClan's beloved medicine cat apprentice, Leafpaw. Now 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 extermination.

But it is not easy to convince the cats to leave. Even if all four Clans agreed to travel together, the dangers waiting for them beyond their borders are impossible to predict. More importantly, even the questing cats have no idea where they're supposed to go. What they need is a sign from StarClan . . . but what they need most of all is a plan to save their missing warriors, or risk leaving them behind forever.