It's a normal part of everyday life.
The dark thoughts, the murderous intentions. Everyone experiences them on a day to day basis, but lock them away for fear of what's within them.
A killer.
A natural born one at that. But, very few kill. Very few unlock their dark thoughts and murderous intentions, and those who do are labeled murderers. Unless of course, they aren't caught.
Jenna Birde unfortunately catches the eye of a man who lets his killer out. The more she interacts with this man, Jenna starts to learn more about Harry Styles, and eventually uncovers his secret. Instead of turning him in however, Jenna lets Harry try and reason with her, soon finding out she too wants to let her killer out.