Can writers make realistic spy novels?

If you have ever read a good spy novel? Then, you know what its like to sit at your edge of your seat reading every word with pure excitement, dying to turn the page and know, what's next? Authors of these said novels work vigorously to produce a one of a kind novel that will captivate their audience with spy adventure. Most of these spy novels are fiction. Unfortunately not all spies are involved in covert deep cover affairs. Spy novels mix fact and fiction to keep readers reading.