The Rise of Nine is arguably the best book series I've ever read. Note that this is the third book of the series and revolves mainly around Four and Six's point of view. Like in each book in the I Am Number Four Series, this book starts with a hook and ends with a cliffhanger-so don't read if your not one of those people who love to have fun. The precedent, The Power of Six, finished where Sam was trapped inside the Mogadorian's hideout and Nine and Four are escaping from it- but that's all I can go to without spoiling everything. I guess, have fun reading.