Bloodmoney by David Ignatius is a suspenseful and engaging read. A small American-run intelligence group has been created; it looks quite a bit like part of the Central Intelligence Agency (CIA), but officially it doesn't even exist.
The experience gave me the idea for a story: A national security reporter discovers that a subminiature electronic device is implanted in his head. He investigates, propelling him into a life-or-death struggle with the spy who'd bugged him.
I knew Le Carré had a fondness for fox hunting and so I rented an authentic Lady's Victorian riding costume. Then I drove to St. Buryan a small village in Cornwall and stopping by the local stables, I arranged to hire a horse for the hunt.