"The Dead Hand" combined with "Command and Control" (http://www.amazon.com/Command-Control-Damascus-Accident-Illu...) makes for very sobering reading. Put the two together, and it's a genuine miracle that nothing bad happened. Of course, we're not out of the woods...
Both are excellent books, BTW, so I agree with the parent poster's recommendation.
Also "One Minute to Midnight: Kennedy, Khrushchev, and Castro on the Brink of Nuclear War" - which is pretty alarming even when we know how it all worked out:
