The Amazing Mrs. Pollifax, by Dorothy Gilman

I probably won't keep writing these up as pretty much everything that I said about # 1 is also true of # 2, though there's less of a voyage of self-discovery as you can only tell the story of "how a widow in her sixties discovered that she makes a really great spy" once. However, the strong supporting cast, travelogue, suspense, humor, and most of all, the delightful Mrs. Pollifax remains. I read this while riding a stationary bike at the gym and repeatedly unnerved my fellow workers-out with bursts of maniacal laughter.

The Amazing Mrs. Pollifax