Tim Jeffreys 
Holburn [EPUB ebook] 

Gael Drake has placed his teenage sister, Ava, in Holburn Academy, a secluded girl’s school in order to keep her out of the clutches of their older brother, a famous medium calling himself The Spirit Whisperer, who wants to use Ava in his stage-shows. Ava, you see, has the ability to raise spirits and communicate with ghosts. Given the news that one of the school teachers has died mysteriously and Ava has gone missing, Gael returns to Holburn to try and find his sister. But doing so means he must face off against the spooks Ava raised during her short time at the school.