The Highway by C. J. Box - 9781781852699 Book
It was Danielle and Gracie's secret. A 1000 mile drive to visit Danielle's boyfriend in Montana. But now the girls have simply vanished and Cassie Dewell's investigation will lead her to the FBI's Highway Serial Killer Task Force, a spate of roadside sexual mutilations and murders and the lair of a predator who styles himself The Lizard King.