Up until this point, I think, the Underland Chronicles were simply entertaining, if somewhat typical, children's reads. Obviously, I enjoyed them -- I got this far, didn't I? But I was enjoying the fun of them, the adventure of them...

However, the fourth Underlander book gets serious. While the notions of family, justice, and fate that are emphasized in all the other chronicles are present here, this book has more weight for two reasons.

Firstly, it's a pretty solid mystery. I felt the ultimate direction of books one to three were fairly obvious from the get go. Not so here. There's a greater sense of danger, as well.

Secondly, the comparisons to the holocaust simply must be made. And this is no light, easy introduction to the notion of genocide. It's grim and brutal.

Like the Harry Potter series, this one has grown with its readers -- fun if you happen to be around for it, not so fun when you are 8 and can't understand why mom wants you to wait to finish the series.

However, as a grownup reader of kids' books, I'm really enjoying it. ( )

In this book, Luxa and Gregor have to find out what's killing the nibblers, or mice, and save them. Somehow, they start a big war with the rats.

I got bored reading this book, and didn't finish. ( )

I think I'm done with this series ( )

Every bit as good as the first three books. ( )

Mice, or "nibblers," are disappearing, and Luxa is determined to find out why. Gregor joins her on a fact-finding mission, and when the true fate of the mice is revealed, it's something far more sinister than Gregor or Luxa has imagined in this gripping fourth volume.