Title: The Code Book
Author: Simon Singh
Description: This is a popularized history of cryptography and cryptanalysis. It runs the range from shift-ciphers to modern public key cryptosystems and quantum key distribution. No prior knowledge of maths is necessary, but can be helpful.
It has been quite some time since I read this book, but I found it incredibly engaging at the time. I know it isn't strictly focused on mathematics, but I am surprised that no one else has mentioned it.