The Lucifer Effect by Philip Zimbardo.
Zimbardo is the psychologist who did the famous Stanford Prison Experiment. This was released in 2007 a little bit after the Abu Gharib scandal came out and he talks about how things like that can happen. How can seemingly normal people end up quickly (and in the case of the SPE within hours) becoming someone totally different.
I'm not gonna lie. It's depressing. Really, really depressing. Added to the fact that the last three books I've read have been this and two Cormac McCarthy books. No wonder I'm feeling so bummed out at the moment. Next book I read I'm determined to make an upbeat one. Any recommendations from you guys?