_The Lucifer Effect: Understanding How Good People Turn Evil_ (Random House, 2007) by Philip Zimbardo, who recruited a bunch of nice Stanford undergraduates, put them in a fake jail, randomly assigned some to be guards and the rest to be prisoners, and watched them degenerate into cruelty & despair, dragging him along with them. Eventually his girlfriend, horrified after a tour, induced him to call a halt.

Power corrupts the powerful and the powerless.