Warriors (Erin Hunter). Original series

Deep in the heart of the forest, four clans of warrior cats coexist in uneasy harmony -- but uncertain times are upon them, and dangers threaten the precarious balance of the forest. Fireheart is a ThunderClan warrior cat now, but his troubles are far from over. As the chill of winter sets in, the cats of rival RiverClan grow restless, while WindClan is weak and facing threats from all sides. As tensions build to an explosive climax, Fireheart faces...

Fireheart, the warrior cat, faces many challenges in his new role of ThunderClan deputy as his apprentice, Cloudpaw, resists following the warrior code, Bluestar weakens, and Tigerclaw continues to haunt the forest seeking revenge.

ThunderClan's darkest hour is upon them and Fireheart, the warrior cat, must protect his clan from a threat unlike any the forest has ever seen, as the time comes for prophecies to unfold and heroes to rise.