@jeruba; I have really enjoyed the Furst series (More than the Larsson triligy with its uber-teenaged-heroine). Furst covers all the T-O-O_’s during the beginning of WWII. Paris, London, Warsaw, Prague, the Balkans, the countries around the Baltic sea, USSR, Germany, Greece, the islands in the Mediterranean, North Africa.The love stories are complicated and mature, the characters are multidimensioneal, the history is accurate, the humor is funny.
Try one and see what you think. For the most part, they stand alone. As is my wont, I listeded to all of them on CDs on an old-fashioned Walkman. These were fun because the reader used all the accents to good avail.
Another interesting series is the Gabriel Allon (art restorer and Israeli spy) novels by Daniel Silva. They use Israel as the focus point and again, the history is accurate.