Anthony Horowitz 
Return to Groosham Grange [EPUB ebook] 

Someone is trying to destroy David Eliot’s school. A year ago, he’d have been happy to see the end of Groosham Grange and its ghoulish teachers. Now, he’s on course to win the Unholy Grail, a cup of magical power presented to the star pupil. But a series of suspicious mishaps sees the gap between David and new boy Vincent King narrow alarmingly. Someone, it seems, is trying to stop David winning — and, worse, threatening Groosham Grange itself!