They vary in how much they delve into the actual spy plots themselves. They are all based in Europe around WWII, and deal with the actual people on the ground doing the spying. It isn't so much about grand spy plots, as it is the people dealing with being in these environments. I definitely recommend them. The first book is "<a href="http://www.amazon.com/exec/obidos/ASIN/0375760008/">Night Soldiers</a>".