The Edge by David Baldacci

The Edge is the latest in the 6:20 Man series (and I'll admit I can't remember why ex-Ranger Travis is referred to as the 6:20 man). Jenny Sikwell is a CIA agent. Her body is found on the rocks of the Maine coast, near where she grew up. Travis is sent by his boss (who is a long-time friend of Jenny's father) to find the killer. While investigating, he comes across a number of recent deaths that he finds suspicious and wonders if everything might not be tied to something that happened to Jenny's sister, Alex, years earlier.

Oh yeah, and someone keeps trying to kill Travis. It's a good mystery story set in a gloomy, insular, rainy version of Maine that the tourist board probably wouldn't approve of.