In hot water at the Copper Kettle

With more than half a dozen acclaimed novels under her belt, Shena Mackay is a writer in her prime: at the height of her powers, possessed of experience, perceptions and contradictions that might elude a greener artist. In her hands, words are spiked, crunchy, fraught with super-sensory meaning: her authorial presence on the page is close to necromantic.

It's with a slightly sinking heart, then, that you pick up her latest book and note that it is another of those Novels About A Fifties Childhood. Mackay is an incredibly vivid, empathic writer. I would believe just about anything she chose to tell me. (Isn't this the power a novelist craves?) And it's not that this book doesn't ring true. It's just that I'd like her to tell me something I don't already know.

It's Coronation year and eight-year-old April's Mum and Dad boldly leave the Streatham smog to run the Copper Kettle Tearoom in Kent. Rural idyll, however (inevitably), it ain't. Despite wild flowers on every table and plaster knickerbocker glories that look "more delicious than the real thing", the tearoom's mostly empty. In fact its most frequent customer is the equally false, searingly sinister Clement Greenidge, whose dachshund's jumping claws leave "swelling pink weals" on the children's legs. The image is acute: Mackay's novel is fundamentally about children's pain, hurt and despair - the damage inflicted by adults in acceptable guise.

"Some of us are trying to make some social headway in this village," says April's Mum - and Stonebridge is a seething comic creation, ablaze with horse-brasses and pickled eggs and all the expected weirdnesses of post-war rural life. When Stonebridge people go to the cinema, they see the end of the film first, so as not to miss the last bus home. There are Bronnley Lemons and Payne's Poppets, Truffle and Nougat chocolates and individual fruit pies. Stodgy people in raincoats talk about each other but still get nowhere near the truth, and say "Never mind" and "All in good time" and "I could murder a cup."

April's parents are loving enough, but preoccupied with social propriety, the Copper Kettle and a new baby. Paralysed by a desire to please the adults around her, April is forced to have endless teas with the scheming Greenidge who is, of course, the epitome of dashing respectability in her parents' unsuspecting eyes.

One child-abuser is much like another and there's nothing new or surprising about Greenidge, but he's still an accurate and chilling concoction. Explosively self-righteous, guilty beyond measure, he's a sexual predator who knows how to charm parents, a con-man whose wheedling conversations with April are emotional blackmail disguised as affection. Dodging his invalid wife, allowing April to shoulder the massive burden of his "love", he furtively masturbates himself to climax in her presence and then just as abruptly sends her away.

Meanwhile, April's best friend, the fiery, red-haired Ruby, daughter of the local publican, is, if anything, an even more dangerously abused child. Deprived, neglected and beaten by her parents (never prosecuted because no one in Stonebridge wants to believe the worst) she finally runs away.

When April stands by Ruby, refusing to tell where she is, the result is a rare moment of violence from April's normally benign father. This single slap momentarily aligns the two girls, but one suspects that acknowledging it robs April of more innocence than all the more obviously abusive encounters with Greenidge. The message is clear. Adults are inconsistent and untrustworthy, children can survive only by suppressing themselves, hiding, refusing to speak, concealing the truth. Failed by those who should care for them, they find no safety, no respite. There's an eerie, moving bravado in Ruby's final bid for freedom, despite the fact it almost turns sour, almost causes her death.

Mackay's novel knows exactly where it's going, what it's doing: its psychology is accurately mapped, sharp and clean. Her prose is flawlessly seductive and comic, confidently wry and sensual. Phrases startle with their lush, awesome originality. A baby's cry is "an orange coloured paper concertina"; coming upon the terrible Greenidge suddenly and unexpectedly is like "walking down a sunny lane and seeing a dead bird in your path".

And yet ... I'm unamazed. Is it just that the descriptions appear too easy, the novel appears to enjoy itself too much? There was nothing sufficiently uncomfortable to be challenging. I wasn't transported. I've been here far too many times. April and Greenidge are already in so much of 20th- century art (the new Et In Arcadia Ego), playing out their sad little tableau in some apparently green and sunny, apparently comfy, retro location.