Gnomon (by Nick Harkaway)

Another pick from the ToB longlist, this is 700 pages of science fiction whose concept led me to put it on my library holds list and whose first few chapters reeled me in for good.  Here's the description:

In the world of Gnomon, citizens are constantly observed and democracy has reached a pinnacle of "transparency." Every action is seen, every word is recorded, and the System has access to its citizens’ thoughts and memories—all in the name of providing the safest society in history. When suspected dissident Diana Hunter dies in government custody, it marks the first time a citizen has been killed during an interrogation. Mielikki Neith, a trusted state inspector and a true believer in the System, is assigned to find out what went wrong. 

And since this doesn't even cover the half of it, here is the rest of the description from Amazon:

Immersing herself in neural recordings of the interrogation, what she finds isn't Hunter but rather a panorama of characters within Hunter's psyche: a lovelorn financier in Athens who has a mystical experience with a shark; a brilliant alchemist in ancient Carthage confronting the unexpected outcome of her invention; an expat Ethiopian painter in London designing a controversial new video game, and a sociopathic disembodied intelligence from the distant future.

I would love to go back and read this all over again, given how much I'm certain I missed the first time, except for the whole "700 pages long" thing.  My favorite of the nested narratives is Neith's in the "real world," which helps ground the rest of them, but I enjoyed all of them.  I love the conclusion this builds to, and the very final chapter is killer.

I put all this description in here to help give you an idea of whether you want to invest in a story of this size and scope and experimental breadth. If it sounds at all up your alley, I definitely recommend it.