Irish author Shan - the pen name of Darren O'Shaughnessy - is a hugely prolific writer of horror novels for children, most of them revolving around vampires (his 'Cirque du Freak' series) and demons. This, book four in the Demonata series, takes place in Ireland 1,600 years ago.The protagonist, Bee Mac-Grigor, is a young trainee priestess struggling to realise her full capabilities until she joins in the fight of the Druids against invading demons from another world. Violent and dark, younger readers may wish to approach with caution.