The scent of magic - Cliff McNish

All over the world children are discovering they have magical powers
as Rachel did when she was abducted by the Witch Dragwena in The Doomspell.
But the reason is that the evil Witches of the planet Ool are determined to avenge Dragwena's death by manipulating an army of children and fighting the good Wizards. Rachel's own powers, and the ability of her younger brother Eric to unmake magic, are tested to the full in a thrilling story in which she has to confront another child as strong as she is herself.
Every bit as exciting and inventive as The Doomspell, Cliff McNish's new book has the same page-turning quality that has made it so popular with young readers.