The story of Stuxnet, the little virus that crept into Iranian control systems and convinced them to destroy some centrifuges. I already knew the basics, but I learned from this book. Over time, there were a few versions of Stuxnet flying around; this might be because the creators didn't think it was spreading fast enough; and, later, that it had spread too far. This book reminds us that reverse engineering is hard; computer security geeks slogged through Stuxnet a long time to figure out what it did. Part of the trickiness: lots of people know general computer security, but not so many people know about centrifuge control systems and/or the systems one uses to program centrifuge control systems.