'Dysfunctional' is the first word to come to mind about the Smart family at the centre of Ali Smith's novel The Accidental. They are all smart: Michael is a lecturer in English literature and a philanderer; his partner, Eve, writes a series of books about non-famous victims of the second world war; her son from a previous relationship, Magnus, is a bright secondary school student who unwittingly triggers the suicide of a fellow student; while her adolescent daughter, Astrid, is obnoxious to the other characters, but appealing to readers.

On holidays in a dreary Norfolk village, the Smarts are transformed by the arrival of an enigmatic 35-year-old, Amber, who seems to have psychic powers. Michael and Eve each think she's a friend of the other. By the time they recognise their mistake, Amber has become the boon companion of Astrid, seduced Magnus and entranced Eve, while Michael dreams of bedding her.

Amber serves as a catalyst of the potential of each of the Smarts, but may be in cahoots with whoever empties their home of everything, as they discover on return from their holiday.

Each chapter captures the voice of a different character, which enables, for instance, the pesky Astrid to emerge in all her gawky appeal. Here, she first discovers Amber asleep on a sofa: 'She is kind of a woman but more like a girl. Her hair is supposed to be blonde but Astrid can see much deeper dark in her hair at the roots of her parting. Her feet are up on the cushions. The soles of them are quite dirty.

'This close up she is younger than Astrid's mother, younger maybe than Katrina, but definitely too old to be a girl. She isn't wearing any makeup. It is weird. Her underarms aren't shaved. There is hair there, quite a lot. Her shins and thighs and the backs of them are also not shaved. It is unbelievable. They are stained with actual hairs. The hairs are like hundreds of little threads coming straight out of the skin.'

Who is Amber? It's not easy to say. It's suggested that she was conceived in, and took her name from, the Alhambra cinema that burnt to the ground after her mother had a fleeting sexual encounter there in 1968.

The year and the site imply all the flimsy promise of an ecstatic new world in which there are no limits.

This is caught in a vivid passage that suggests the novel is about the spirit of the age: 'I was born in the year of the supersonic, the year of multi-storey multivitamin multitonic, the highrise time of men with the technology and women, who could be bionic, when jump-jets were Harrier, when QE2 was Cunard ... I was formed and made in the Saigon days, the Rhodesian days, the days of rivers of blood. Apollo 7 splashdowned, Tunbridge Wells was flooded ... They shot the king in Memphis, which delayed the Academy Awards telecast for two whole days. He had a dream, he held these truths to be self-evident ...'

The immediacy of the writing seems to reflect an age that is over-stimulated, exciting but also confusing. For all its vividness, the main thrust of The Accidental remains hazy.