Poppy Shakespeare, by Clare Allan

Clare Allan's first novel, Poppy Shakespeare, has many echoes. The most obvious is One Flew over the Cuckoo's Nest, but perhaps Catch-22 is more fitting. Kafka and the newspeak of Nineteen Eighty-Four also spring to mind. It's an ambitious mix that could so easily have fallen flat on its face, but Allan has pulled it off beautifully.

A monolithic skyscraper dedicated to the care of the mentally ill looms over a London sink estate that hums with chaos by day and goes eerily quiet at night as the collective medications of the residents kick in. In the skyscraper, "the madder you was, the higher you gone" till you reached the eighth floor, "The Floor of No Return". Every day, a motley cast of inadequates go up the hill from the estate to the Dorothy Fish Day Centre, an awful place on the first floor. Anyone who's ever sat in a dole-office or hospital out-patients will recognise that air of resignation underpinned by hysteria, the tired carpet, the lone plant. Here, the scabbed, scarred, greasy-haired characters live out their lives, finely poised between coping and crashing.

Our perfect guide to all this is narrator N, food and ash-stained, graceless in her tracksuit bottoms. "Don't get me wrong. I ain't after the sympathy vote," she says. "Fact is," she assures us, "I been dribbling since before I was even born. My mum was a dribbler and her mum as well." N is a hard case, her crab-shell the result of the catastrophic upbringing she relates with supreme insouciance: "When Mum weren't twirling her tights round her head, she was hanging off bridges and slashing her arms and swallowing pills by the bottle and shit, till one Tuesday evening... she jumped in front of a train and that was the end of it."

Who better to show around the new girl, Poppy Shakespeare, introducing her to such characters as Astrid Arsewipe, Middle-Class Michael, Schizo Safid and "Sue the Sticks"? Everything is inverted. Here, to be normal is to be different. To the consternation and deep mistrust of the other daycare patients, Poppy can't wait to get out of the Dorothy Fish. No offence, she assures them, but it's just that she isn't mad and this is all a terrible mistake. This bemuses the others, who dread nothing more than finding themselves suddenly adrift, alone, in the real world, and who spend the final weeks before their yearly assessments refining their personality disorders like sixth formers anxiously working towards A-levels.

In order to get funding for the only lawyer who specialises in this field, Poppy needs to be receiving "Mad Money", something which can only be accessed through a vast multi-layered web of red tape, and for which various levels of mental disturbance must be proved by ticking boxes. When her application is turned down N embarks upon training Poppy in madness in order to qualify her for the money to pay to prove that she is not mad. Go figure.

Clare Allan's light touch offsets the darkness. Articulating the inarticulate, deceptively skilful, this is an outstanding novel, acknowledging and transcending its many influences to create something all its own.

Carol Birch's 'The Naming of Eliza Quinn' is published by Virago