The Heat of the Day (1948)
by Elizabeth Bowen
Elizabeth Bowen is a 1001 Books evergreen. She's got a book from the 1920s (The Last September), which is about the plight of the Anglo-Irish landholder class during the Irish Revolution. She made into the 1930s with To The North. All of her books feature female characters with modern sensibilities, and Stella Rodney, the heroine of The Heat of the Day, is no exception. The Heat of the Day is somewhere between a spy novel and a "modernist" book of relationships a la Virginia Woolf (the back jacket calls The Heat of the Day "Graham Greene meets Virginia Woolf."
The main difference between The Heat of the Day and the nascent spy novel genre is the utter lack of action in The Heat of the Day. Stella is in love with Robert, who is maybe a spy for the Germans. Harrison is a counter-intelligence agent infatuated with Stella, he seeks to blackmail her by threatening Robert. Events spool out in not entirely predictable fashion. Bowen also includes a b-story about Stella's son from a brief first marriage which ended in divorce and the war-time death of her husband (in World War I.) The two plots link together in a way that ultimately places the spy story in the narrative background, as a means for Stella to explore her feelings about men, sons and everything.