The Highway by C.J. Box

When teenage sisters Danielle and Gracie vanish on a road trip through rural Montana, their disappearance sets off a desperate search. Former sheriff's investigator Cody Hoyt, fresh off a personal loss and barely holding his own life together, teams up with his new partner Cassie Dewell to uncover what happened. What they find is a chilling web of truck stops, long-haul routes, and a sadistic killer known only as “The Lizard King.”
Inspired by real-life long-haul trucking crimes, The Highway is a heart-pounding, atmospheric thriller—and the basis for the hit TV series Big Sky.
 
Based on real cases: The story taps into the eerie reality of unsolved highway abductions.
Unforgettable villain: “The Lizard King” is one of the creepiest, most chilling antagonists in crime fiction.
Dual investigation POVs: Follow Cody’s experience and Cassie Dewell’s growing role as a capable and sharp investigator.
Setting you can feel: Montana’s wide-open highways and isolated truck stops make for the perfect backdrop of dread.
Now a TV series!: If you liked Big Sky, you’ll love the book that started it all.