The Shadows - A Poppy Farrell Mystery, #1

Your Shadow follows you where ever you go..... From the moment she enters the world of her new boarding school, Blight's Academy, 14 year old Poppy Farrell, finds sinister forces at work. From a horrifying encounter on a train platform, to evidence of a murdered student in the woods that surround the ancient, gothic buildings, life at Blight's Academy grows more horrific by the day. Poppy and her friends, Clair and Georgie, must outwit their Shadows, older girls assigned to mentor them by following them wherever they go.
There is a dark secret at the heart of Blight's Academy: disappearances, deaths, and occult conspiracies pervade the wooded grounds, flicker in the stained glass windows, tinkle like a music box lullaby through the turreted halls....