The three Clans of the valley have been at peace for moons, now. EmberClan, RainClan, and SilverClan have dealt with each other without severe bloodshed and there haven't been many struggles. The most that they usually worry about is sudden outbreaks of disease and the slight lack of prey.
Leaf-fall is turning into leaf-bare. Food is suddenly getting scarcer as the days grow longer. Yet, peace is still flowing in between the Clans... somewhat. That is, until something terrible happens, and the peace that has lingered will finally be blown away by the cold winds.
What is this terrible thing? You'll just have to find out.