Hayley and Grace: The Mysterious School

An old boarding school. Thin walls. An old hidden room, once a classroom.
After their mothers death 5 years ago, their father, Mark, sends his two daughters off to a boarding school called, Oak Grove school for girls.
But the finger of suspension goes to mischief maker, Hayley Harris. Dresses goes missing, then blankets, food even. But who is it? Can twin sisters, Grace and Hayley discover the thief? Or will Hayley remain the suspect?