I was a little confused by the title, since very little in this book had anything to do with breaking through a computer firewall. It was a neat little story about a typical gamer, Josh, who is struggling to find himself and his social network in a new high school. Also struggling with friendship, both past and present. But our gamer finds a strange mod on his favorite game where his entire town is modeled in fairly exacting detail.
So the mystery is who did this, why, and will they ever come back? When a friend hacker gives admin abilities to Josh, he begins adding and messing around with the town mod, creating a castle with impervious automated-defense systems (is THIS the firewall of the title?). Until the original creator comes back and is not pleased, and mysteries begin to unfold.
A nice, short, young-adult book with a bit of computer knowledge, a bit of teenage angst, and some lessons to be learned. Josh is learning to deal with his police officer Dad, and how to fit in in high school. This should appeal to many teenagers in similar situations. Well-written, overall, if somewhat abrupt in how the story wraps up. But it also certainly doesn't drag on, and might be a good way to get your gaming youth into a quick book reading.