The Demon Headmaster takes over - Gillian Cross

It's amazing! The Hyperbrain is a super intelligent computer that works by accessing the human brain. In the wrong hands, though, it could spell disaster. The new Controller at the Artificial Intelligence Unit seems horribly familiar but Dinah and her friends know that the Demon Headmaster has been defeated. Hasn't he?Great fun and just 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!

It's exciting stuff that will have you on the edge of your seat until the very end
Primary Times

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