The Demon Headmaster strikes again - Gillian Cross

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!

I would recommend this book.
It was so good it deserves reading twice.
Lincolnshire Echo

This will be greatly enjoyed.
Books for Keeps

Gillian Cross is one of the best children's novelists today and her stories of the Demon Headmaster are both fun and quite frightening.
Daily Telegraph