The first book is called Into the Wild.The other 5 books in the series are Fire and Ice, Forest of Secrets, Rising Storm, A Dangerous Path, and The Darkest Hour. The series follows Thunderclan, a clan of wild cats that live in the forest ,and lets you experience their life through the point of view of one particular cat named Fireheart. Follow Fireheart and his clan as they fight Shadowclan, Windclan and Riverclan for their territory and survive forest fires, floods and even experience shortage of food. This series is really great and I suggest it to anyone. The series continues in a series called Warriors: The New Prophecy. There are 4 books in this series. They are Midnight, Moonrise, Dawn, and Sunlight. I suggest you read this great books by Erin Hunter.