Based on The Haunting by Natasha Preston.

Penny's trying to forget about her ex, Nash. His father was arrested for the brutal murder of four teenagers on Halloween last year. Penny's parents have forbidden her to have anything to do with Nash or his family. It's hard not to think of what happened as spooky season gets underway–but she's trying. You're Penny's best friend. But, when a copycat killer shows up, it's believed to be Nash or his sister Grace because the town despises them.