What is warriors power of 3 Outcast about?

Answer 1

There is trouble happening in the Tribe of Rushing Water, and they fetch Stormfur and Brook to help fight off the trouble. Along with the two comes Squirrelflight, Brambleclaw, Crowfeather, and Tawnypelt. After excessive begging, Jaypaw, Hollypaw, and Lionpaw get to come, too. (possibly Leafpool)

meanwhile, Jaypaw is desperate to learn the secrets of the ancient cats who prowl his dreams; Lionpaw and Hollypaw feel drawn to the mountains too, though for different reasons.

In this book you start to get a better look at who the three of them are going to turn out in the future.