The Demon Headmaster

When Dinah is fostered by the Hunters she thinks her biggest problem will be
fitting in with her foster-brothers, Lloyd and Harvey. However, once she starts
at her new school it's clear that there's more to worry about. All the
children, apart from a handful including Lloyd and Harvey, are too
well-behaved-robotic almost-and oddly keen to please the creepy headmaster.

The three children set out to discover the nature of his influence over
everyone . . . but then Dinah finds herself saying and doing things she has no
power over. Soon they uncover the headmaster's wicked plan. Controlling the
school is just a practice run. He has set his sights on dominating the entire
nation! The children must foil him before he succeeds . . . but with Dinah
under his spell they've got a challenge on their hands."