I. St. George's Academy

Charlotte "Charles" Willow has a mysterious encounter with a pair of mysterious, notorious twins at St. George's Academy, when she sneaks out of a party. One year later, when Charles had almost forgotten about it, she is faced by a mysterious person in a mirror that appeared in the hallway. As soon as she slips in through the mirror, she is faced by a peculiar world based within St. George's Academy, with dangerously peculiar threats.........

THE story cover doesn't belong to me.