The trap / Catherine Ryan Howard.

Stranded on a dark road in the middle of the night, a young woman accepts a lift from a passing stranger. It's a nightmare that every girl is warned about, and she knows the dangers all too well - but what choice does she have? As they drive, she alternates between fear and relief - one moment thinking he is just a man doing a good thing, the next convinced he's a monster. But when he delivers her to her destination, she realizes her fears were unfounded. And her heart sinks. Because a monster is what she's looking for. Inspired by a series of unsolved disappearances, 'The Trap' is a startling thriller.