My dad had this book from the scifi bookclub - from when he was a teenager, I think. I borrowed it from him this summer and just finished it. While I was reading it, it scared the hell out of me. It gave me my best understanding of what it must have been like to live under the threat of nuclear war in the 50s and 60s (I was born in 1979).
The story is told from the view of a guy who must "push the button."
Well-written and poignant. Perhaps a bit naive now, it still got to me.