Caroline was driving and she heard a loud pop from behind her. She snapped her attention back and looked behind her and see that there was a car wreck behind her.
She heard a gunshot and that's what the loud popping sound was. They were wondering if the guy in the blue pickup was a suspect for firing the gun or not.
The blue pickup that was at the scene when she got in the wreck. Her roommate was being very weird about everything. And she was moving back to her parents house so she could live with them.
They know that Ron Cagle did it because he had the same pickup and its license plate was just change. It was obvious. The paint on the truck was just scraped off so you could tell that the blue pick up was that one.
They figured out that the guy with the pickup was Ron Cagle. So the ending was she is back and well.