As told by Emily Dunbar...
One night a woman went out for drinks with her girlfriends. She left the bar fairly late at night, got in her car and onto the deserted highway. She noticed a lone pair of headlights in her rear-view mirror, approaching at a pace just slightly quicker than hers. As the car pulled up behind her she glanced and saw the turn signal on — the car was going to pass — when suddenly it swerved back behind her, pulled up dangerously close to her tailgate and the brights flashed.
Now she was getting nervous. The lights dimmed for a moment and then the brights came back on and the car behind her surged forward. The frightened woman struggled to keep her eyes on the road and fought the urge to look at the car behind her. Finally, her exit approached but the car continued to follow, flashing the brights periodically.
Through every stoplight and turn, it followed her until she pulled into her driveway. She figured her only hope was to make a mad dash into the house and call the police. As she flew from the car, so did the driver of the car behind her — and he screamed, "Lock the door and call the police! Call 911!"
When the police arrived the horrible truth was finally revealed to the woman. The man in the car had been trying to save her. As he pulled up behind her and his headlights illuminated her car, he saw the silhouette of a man with a butcher knife rising up from the back seat to stab her, so he flashed his brights and the figure crouched back down.
Moral of the story check the back seat.