A Wanted Man by Lee Child

Jack Reacher is just trying to hitchhike to Virginia to meet a woman when he's picked up by a car carrying 2 men and a woman. All he wants is a ride but Reacher ends up in the middle of a murder investigation/homeland security situation. And it takes all his wits and ingenuity to stop a nefarious plot and bring the bad guys to justice. If you're new to the Jack Reacher series, the hero is an ex-military man who now roams the country helping people out. The last couple of books have been very violent, so I was glad to see that, in A Wanted Man, Reacher relies mostly on his brains rather than his brawn. I read the whole book in a couple of days over a busy Thanksgiving weekend so that should tell you how engrossing the story is. If you're new to the series, start with Killing Floor.