[Found!] Need help remembering / identifying a science fiction story

[Andrew]

Found! (http://en.wikipedia.org/wiki/City_at_...)

Hello esteemed readers -

I've been driving myself crazy trying to remember a book and I'm hoping you all can help me.

What I remember:
People are living in a walled city that is protected by "reality generators" - or something of the like. There are huge towers, one of which has a library in it. The generators are failing and are predicted to stop working soon.

A group is being assembled to travel out of the city.

There is an enemy general outside in the wilderness. There is a risk of madness / chaos / dissocation when leaving the city.

I think that it was the first book in a series, but again I can't recall the work.

Thank you in advance for your help.

Andrew

[Candice]

I don't know the book, but it sounds interesting!

[Serena]

?

[Andrew]

Ron - You're amazing. That's exactly the book (http://en.wikipedia.org/wiki/City_at_...). Thank you from the bottom of my tormented brain!

[Candice]

Lol!!! I have absolutely read that and loved it, and didn't even connect the two! Oh man, the shame.. I only read it two months ago.

[Zac]

That DOES sound intriguing, and everything I've read of Bear's so far I've loved... I'm going to have to check this out!