7 Stones: Book 1: Frozen

Eight will gather, four will die. Four will come from water and sky. To earn the Elements they must try. Or else the seven stones will die. Thistlepaw and Mapletail are apprentice and mentor until a mysterious cat arrived at their clan during the worst leaf-bare they have experienced. To make it worse, the mysterious cat delivers a prophecy: "The white wolf will come to battle the night. It shall become one with the wolf, unless the cold can become heat, and thaw the white wolf's claws."