BOOK REVIEW / Murder in the madhouse: The dying of the light - Michael Dibdin: Faber, pounds 9.99

ROSEMARY TRAVIS, the Miss Marple of this pastiche Agatha Christie, descends the stairs of a large country house. Her stocking seams are straight and her gaze is steady; she is the right sort and she knows it. She enters the lounge - lounge? 'No, no,' I wrote in the margin, tripping straight over the book's first clue. For the house is an institution and the Cluedo-type cast assembled in the autumn dusk - 'It's only September you know. Or October at the lastest' - are all old, mad and derelict, consigned to a living hell by heartless families.

The place is run by a psychotic brother and sister, with a little help from a Doberman. Deprived of all contact with the outside world, the residents cling to meaningless rituals, knitting squares only to unravel them, talking into a disconnected telephone, playing a soundless piano. Their warders are eager to rub their faces in squalor and mortality. Death stalks the corridors, a 'ruthless and anonymous killer against whom the combined forces of civilisation has so far proved powerless'.

Rosemary Travis accommodates the horrors of this life by weaving detective stories around her fellow inmates; thus she escapes the 'tyranny of the real'. Her imaginative life so enmeshes her that when for one evening the old people unite in violent emotion and even resist their brutal matron, she recoils in distaste; they are breaking her rules, deviating from their cardboard characters. A policeman arrives, to investigate a death. He has a keenly interrogative mind: 'What is truth? What's it all about, Alfie? Where are the snows of yesteryear? How much is that doggie in the window?' He too prefers the unreal. He would like to be Inspector Wexford on TV; in the back of his mind Accrington Stanley FC are forever playing their biggest match.

Michael Dibdin is, as usual, horribly, monstrously funny and his nasty phrases linger in the mind (carcinomata are 'sprouting like fungi on a dead tree'). But the power of his images and the force of his wit so dominate the book that one loses interest in the delicate shifts in truth and untruth, reality and invention of the fairly minimal plot. His The Last Sherlock Holmes Story was more successful as a pastiche because he was able to sustain the mood of the original. Agatha Christie is too frail for the Dibdin touch. None the less this is a merry and maddening jeu d'esprit, so long as your own esprit can cope with remarks like 'I'm not sure that I perhaps don't not believe in it any more.'