Vanished, Private Justice Series by Irene Hannon and published by Revell Publishing.
Reporter Moira Harrisons is lost. In the dark. In a thunderstorm. When a confusing detour places her on a rural, wooded road, she's startled by the sudden appearance of a lone figure caught in the beam of her headlights. Though Moira jams on her brakes, the car careens across the wet pavement--and the solid thump against the side of the vehicle tells her she hit the person before she crashes into a tree on the far side of the road.