The story begins with a group of people playing a card game of some sort, I can't recall what it was exactly, but it had some sort of team aspect to it. There were three or four players. One of them was a woman and she was nervous about the way she was playing and didn't want to let her partner in the game down. Then some event occurred, probably the alarm went off, and they were forced to stop the game in order to go to the shelter.
That's basically all I remember. I started this book when I was at my friend's house and didn't get to finish it or advance any further. I'm 99% sure that the author is Robert Heinlein though.
I would really like to finally read it, so if someone comes up with the name that will be great.