This book details a lot of information dealing with why cryptography is important on the Internet and how some styles of cryptography are easily broken allowing others to eavesdrop. It then explains how different encryption styles are implemented, the standards that are out there, including some real world examples of things going right and how thing can sometimes go wrong.
There are chapters on encryption protocols. Lastly there are a few chapters on the politics, people and flops in the cryptography world.
It also gives a list of external references for further reading.
The book contains a lot of simple diagrams that I found helpful with some of the descriptions, though most were very well written descriptions.
If you are into cryptography it seems to be a good book for helping to understand how things are done and the pitfalls that can get into you if you do not know about them.