The Code Book by Simon Singh
I’m sorry, you can no longer win $15,000 by reading this book. It was the announcement of the solution to the 10 cipher challenges, located in the back of The Code Book, that made me aware of this book. Money aside, if you are interested in learning of the history of codes and ciphers, this book is for you! Did you know that Mary Queens of Scots was killed by Queen Elizabeth, because her code was not strong enough to foil the code breakers of the time.