Warrior Cats

My third grade son is really into these books - the Warriors series by Erin Hunter. It's about clans of cats and a main character cat named FireHeart. Other character names are Bluestar, Graystripe, Sandclaw and Tigerclaw. Alex and his third grade classmates love these books. He's already into book #4 of the series of 16 books. I think this might be the next craze after Harry Potter.