A quiet family road trip. A nearly-empty tank. A lonely stretch of highway at dusk. Arthur and Samantha just wanted to be kind. They live by the Good Book, help thy neighbor. When they spot a solitary hitchhiker on the shoulder, thumb out, face half-hidden under a cap, they slowed down. They stopped. They opened the door. The heater hums. The radio plays soft oldies. Everything feels... normal. At first, but when the locks click down and the road stretches darker ahead, the family realizes that kindness can be a fatal mistake. They are miles from help. No signal. No way out. Trapped in their own car with a monster who has done this before. He has been called the Cliffside Killer. The newspapers say he leaves no trace. Now he is in the backseat. And he is not getting out until he is finished.