It Lives in The Mirrors

Rylin is a normal girl. She has two close friends who are by her side, always, no matter what. They have done everything together since they all met when they were seven. That was nine years ago. But when people from their school start going missing, her and her friends have no idea what to do and have to try and keep everyone they love safe. Who is taking them? Why are they taking them? But most importantly, why does everyone keep hearing things in the mirrors at night?