Restless by William Boyd
It is 1939. Eva Delectorskaya is a beautiful 28-year-old Russian emigree living in Paris. As war breaks out she is recruited for the British Secret Service by Lucas Romer, a mysterious Englishman, and under his tutelage she learns to become the perfect spy, to mask her emotions and trust no one, including those she loves most. Since the war, Eva has carefully rebuilt her life as a typically English wife and mother. But once a spy, always a spy. Now she must complete one final assignment, and this time Eva can't do it alone: she needs her daughter's help.