If you want a good series that's more "realistic" but along the same lines of interesting cat / mouse play, check out the John Rain series by Barry Eisler. It'

If you want a good series that's more "realistic" but along the same lines of interesting cat / mouse play, check out the John Rain series by Barry Eisler. It's extremely, meticulously well researched. Oh, and it's more recent, so you can see how it works with modern day technology rearing its head.