A Colder War by Charles Cumming

A classic old-school espionage novel, with some intriguing plot twists.  Tom Kell, an out of favor British agent is sent to investigate the suspicious death of another British agent in Turkey.  Kell is tasked with searching out a potential mole in the British or American services in Turkey - and the plot begins its twists and turns.  Cumming is great at bringing us into the world of spies, where nothing can be accepted on its face.  382 pages

A Lesson In Secrets: A Maisie Dobbs Novel, book 8, by Jacqueline Winspear

1932 finds Maisie Dobbs being asked to take an first assignment for the British Secret Service!  She leaves her business in her assistants' hands and goes undercover to Cambridge as a Classics professor—and leads to the investigation of a web of activities being conducted by the emerging Nazi Party.

When the college's controversial pacifist founder and principal, Greville Liddicote, is murdered, Maisie is directed to stand back as Detective Chief Superintendent Robert MacFarlane and Detective Chief Inspector Richard Stratton spearhead the investigation. She soon discovers, however, that the circumstances of Liddicote's death appear inextricably linked to the suspicious comings and goings of faculty and students under her surveillance.
To unravel this web, Maisie must overcome a reluctant Secret Service, discover shameful hidden truths about Britain's conduct during the Great War, and face off against the rising powers of the Nationalsozialistische Deutsche Arbeiterpartei—the Nazi Party—in Britain.
352 pages