This is the sequel to I Am Number 4. It is very much a sci-fi book, taking place in a world when aliens from the dying planet of Loren have come to earth in order to escape the race of aliens that have caused their planets destruction - but they cant evade the Mogadorians forever.
The plot to these books is simple (if you are used to the whole sci-fi/fantasy genre). The last survivors of an alien race have come to earth. They are in the form of pairs of children and their guardians. Each child has a number, from one to nine, and they cannot be killed out of order, except if they come into contact with another number.
You may notice I said 'killed' there. That's because the race of aliens that caused the destruction of the planet Loren have the same plans for earth. What's stopping them is the survival of the children - now teenagers. But the race is on, as now that they are older they have begun to develop legacies (powers).
The first book is focus around Number 4, whereas this one switches between Number 4, and Number 7.
I don't want to give too much away, and the background information there is about the same as you would get if you read a review of the first book, so I wont say much more.
I read this book in an odd manner. It's the kind of thriller that you cant put down - except I did, and I read it slowly. I think it was because I didn't have much time, but still, maybe it says something.
It was kind of light on the emotions (but then again, I have high standards for things like that... you'd be hard pressed to hand me a book that really makes me feel), but it's a good book, over all.