Like war, writing fiction for young people can often be a "brain-spattering, windpipe-slitting art". Anybody raised on the Brothers Grimm can probably get through American Psycho without turning a hair. But Darren Shan set new standards for goriness in his novel Lord Loss (2005), with a scene in which Grubbs Grady, the teenage narrator, came home one day to find his parents and sister being brutally murdered by what turned out to be demons from another universe.Poor old Grubbs's problems had hardly started. Lord Loss was the inaugural volume of The Demonata, a sequence that looks as though it will run for as long as Shan's bestselling, 12-volume "Saga of Darren Shan". The latest book in the series, the third, is called Slawter (HarperCollins, £12.99), a title that suggests it is best read doing whatever is the literary equivalent of watching the TV from behind the sofa.Well, it's true that a lot of people get brutally murdered in Slawter. The plot sees Grubbs involved in the making of a horror film in which the rampaging demons turn out not to have been made by the special-effects department. There follows butchery on a grand scale, orchestrated by the Demon-master Lord Loss, who is about as evil as you would expect for a man who has a snake-filled hole where his heart should be.But Shan is not just a mindless purveyor of grisly thrills. Like all good fantasists, he is interested in showing the reactions of ordinary people to extraordinary events. In this story, Grubbs discovers that he is developing magical powers, but, after his experiences, finds the idea of any sort of involvement with magic abhorrent. Shan's portrayal of his troubled hero is convincing and affecting.