Challenger - Paul Butler Thrillers, #3

Paul Butler is a widower, an ex-cop, and a self-confessed car nut. He's an ordinary guy with an out-of-the-ordinary job . he's chauffeur to multi-billionaire David Harrington. When news of a death in the family belatedly reaches Harrington, he is somewhat surprised to find that his uncle, a man he barely knew, has mentioned him in the will. Harrington invites Paul to accompany him on a road trip to attend the reading of the will.
Paul meanwhile, wonders . what on Earth do you leave a billionaire when you pass away? While visiting with his widowed aunt, Harrington mentions to Paul that he would like to drive past where his uncle used to work. However, after a friendly enough chat with the guy on duty at the factory security gate, it's only a short time later that they find themselves being warned off by one of the deputies from the local sheriff's office. The weird lack of activity at the factory, plus a story about what might be hidden underground in the area, as well as the local deputy apparently watching every step they take, soon combine to arouse Harrington's curiosity.
Even reluctant Paul has to admit to wanting to know more once they begin to plumb the depths of the area surrounding the aptly named Secret Town. When they realize what they've uncovered, claiming Harrington's inheritance becomes the least of their problems.