Warriors: Secrets of the Clans by Erin Hunter

Now the truth can be revealed

Look within to find:

• The mystical origins and secret legends of the Clans.
• An insiders' tour of the Clan camps and territories.
• The histories and characters of each Clan, and information about their leaders and medicine cats.
• Knowledge of cats outside the Clans.
• The tenets of the warrior code.
• Prophecies and omens, and how they have been fulfilled.

And many more truths about the secrets, beliefs, and daily lives of the cats of the Clans.