Restless by William Boyd

I was surprised to find this book on a list of the "best" spy novels, but not when I read it. It's not only a good one but it's different.

A woman tutoring foreign students in English while she half-heartedly completes a dissertation in history visits her mother in a picturesque village a short drive away. Her mother is a widow, in reasonable good health and in possession of her faculties. But Sally (the mother) has decided it's time to tell Ruth (the daughter) the truth about her life. She's really Russian (well, she had an English mother)--left with family after the Revolution, ended up in Paris by way of Shanghai--where the family exists as "stateless persons".  She's persuaded by a dashing British spy to work for him in return for British citizenship etc. 

The chapters alternate between Sal's memoir of her life as a spy and Ruth's life in the present. The two converge as Sal urges Ruth to help her track down the suave British spy who seems to have tried to kill off everyone who worked for him during the war. Sal alone escaped.