I just finished rereading the late Helen MacInnes' first novel, Above Suspicion, published in 1941 and strangely resonant in these modern unsettled times. In my youth, I was very partial to spy novels and read most of MacInnes and other writers of the genre. I remember liking hers for the strength of her female characters and enjoying the detailed depictions of Germany and Austria. I still read spy novels in addition to mysteries. For example, I've read and re-read Len Deighton's terrific Berlin novels with Bernie Sampson, stuff by Alan Furst, most of Le Carre, and stuff like Francine Mathews' recent Jack 1939, that also deals with the same fraught eve of World War II period as Above Suspicion, with a twist.
An Oxford professor and his pretty wife, Richard and Frances Myles, planning a mountain climbing holiday in the summer of 1939, are asked by a an agent of the British Secret Service, one of their friends, to see about a missing agent somewhere in Europe. While nonchalantly climbing mountains with just wool socks and good hiking shoes (I found this as amazing as the spying), they also put their fluent German and quick wits to good use. The story is really suspenseful as the Myleses are increasingly endangered as they follow a trail of agents through France, Germany, Austria, and Italy. Along the way, they convince an American newsman, who had planned to be neutral, and a fellow brit., an Oxford acquaintance, that war with the heinous Nazis is unavoidable. MacInnes paints a fascinating and ominous picture of a changed Europe bowing under the increasing weight of the Nazi fist.
The book was made into a Hollywood movie in 1943 with Joan Crawford and Fred MacMurray where the Myleses are on their honeymoon and Americans. I don't remember seeing it but I am going to seek it out.
