The Secret Of Drearcliff Grange School by Kim Newman (epub, mobi) [BluA]

Summary:
When her mother finds her sleeping on the ceiling, Amy Thomsett is sent to Drearcliff Grange School in Somerset. Although it looks like a regular 1920s boarding school, Amy learns that Drearcliff girls are special, the daughters of criminal masterminds, outlaw scientists and master magicians. When one of the girls in her dormitory is abducted, Amy and her friends must form a secret, superpowered society called the Moth Club to rescue her.