Audiobook "Without Mercy" by Lisa Jackson

Ever since her father was stabbed to death in a home invasion, Julia “Jules” Farentino has been plagued by nightmares. Her half-sister, Shaylee, now seventeen, has had her own difficulties since the tragedy, earning a rap sheet for drug use, theft, and vandalism. Still, when Jules learns of her mother’s decision to send Shay to an elite boarding school in Oregon, she’s skeptical. Blue Rock Academy has a reputation for turning wayward kids around — but one of its students went missing a few months earlier and her body has never been found.

On impulse, Jules applies for a teaching job at the Academy. Shortly before Jules arrives, a student is found hanged, another near death, and a hysterical Shay believes it’s murder. Then another girl is found dead. There’s no doubt something sinister is at hand. And Jules has become the next target of a bloodthirsty killer without limits, without remorse, without mercy…