Gillian Cross 
Demon Headmaster Strikes Again [EPUB ebook] 

The Hunter family have moved house and can finally forget all about their encounters with the Demon Headmaster . . . or can they? Just as they start to relax, Dinah, Lloyd, and Harvey notice that the villagers are all speaking the same robotic phrases. This can only mean one thing . . . the Demon Headmaster is back and this time he’s planning a terrifying experiment. Great fun and a little bit frightening, Gillian Cross’s Demon Headmaster books still hold readers under their hypnotic spell. Fast-paced and full of adventure, they’re impossible to resist!