NIGHT SCHOOL 3 : FRACTURE - Little Brown UK

"Cimmeria has been more than a school for Allie, it's been a safe haven. But no longer.
A nefarious group - one that is tied up with Allie's family in ways she could barely imagine - is trying to destroy everything Cimmeria stands for.
Even worse, it's clear that somebody they eat with, sleep with, train with is betraying them. There's a spy in Night School. As the paranoia grows and the fights begin, it's not an attack from outside they need to worry about..."