The God's Eye View by Barry Eisler
What happens when the NSA domestic spying program that Snowden didn't know about is on the verge of being exposed, and the NSA director is a megalomaniac sociopath with a squad of trained assassins at his disposal?
This book is fiction, as far as we know. However, everything in it seems plausible enough. I don't want to give away too much plot, but there is nothing in this book that the "9-11 was an inside job crowd" doesn't already believe. Take a program that can listen in real time to just about every conversation happening anywhere, add in the the kind of correlation that big data makes possible, one psycho NSA Director, some government assassins, and a reluctant whistle blower; and you get one hell of an entertaining story that is just close enough to reality to make you wonder.