There's a scene near the beginning of John Wyndham's The Day of the Triffids in which the two main characters, who have so far survived the global catastrophe erupting around them, break into a mansion block somewhere near Regent's Park. They find a luxury flat and grab a last chance to dine in style: they nibble on an "expensive-tasting" pâté, and sample an "unpriceable" brandy. They wonder when they shall ever taste fresh oranges again. Wyndham was of course writing in 1949, when oranges and pâté were for most British people matters of distant memory.

There is a similar scene in The Age of Miracles, a US debut which sparked a bidding war among publishers: the 11-year-old narrator, Julia, enjoys a celebratory meal of pasta and tinned pineapple, later reflecting with adult hindsight that it was the last time in her life she ate pineapple. This is well into the book, when the global catastrophe it depicts is long under way.

It seems that the Earth's rotation is for some reason decelerating. It becomes known to all as the "slowing". The days and nights get longer  by the end of the book there are six-week periods of daylight, then darkness. The birds, whales and grasses start to die; radiation increases as the magnetosphere undergoes irreversible change.

Scientifically, much of this is a bit suspect as well as being inconsistent. No explanation is given for the slowing, which in the real world would be a result rather than a cause, and the result would follow earlier events of unimaginably violent upheaval, including changes to the orbit of the Moon. But never mind all that  it is only the background. The front story is Julia's. She lives in a middle-class community somewhere near San Diego. Her concerns are those of many 11-year-old girls: the best friend who betrays loyalties, the buying of a first bra, the death of a grandfather, the suspicions that Dad is having an affair.

The global upheavals go on and a new sickness appears called the slowing syndrome. Like Hollywood Disease the syndrome incapacitates tastefully  this variation arises when worries about panic-buying kick in. The mother starts stockpiling peanut butter: 50 big jars stashed under the bed.

But wait! The school bus still arrives every morning, the supermarkets are open, Dad drives around in a Volvo, the electricity is on, so is the water, TV and the internet are working, the roads get fixed. Grapes, pineapples and wheat vanish but somehow there are limitless supplies of peanut butter and pizza.

What of the outer world, also slowing? We hear of riots in Paris, and the developing countries are having a tough time  the head of the Red Cross is quoted as saying that unlike the US "they simply lack the financial resources to adapt". That's chops, then, for anywhere without the dollar.

Thompson Walker's writing is flat, efficient, careful. It reveals all the hallmarks and acquired craft skills of the creative writing course: a persistent blandness, an incorruptible awareness of political correctness, but also a kind of defensive knowingness. She has been taught to keep the plot moving, to produce small surprises or reversals. But she also writes with a total lack of irony, of awareness of the larger world. Characterisation is done by numbers: as soon as the soft-eyed boy with the skateboard appears you know that not only will he get the girl, he won't make it to the end of the novel.

This is the kind of book, with its allegedly vast payments to the author, that will suck the oxygen out of bookselling for several months. It will mostly be sold at substantial discounts in supermarkets and online. It will find a kind of success, but in almost every other way it is a sorry and pallid failure.

 Christopher Priest's The Islanders is published by Gollancz.

We live in unnerving and uncertain times for publishers. Just this morning, as I sat to write, I received an oddly buoyant letter from my (very big, long-established) American publisher, explaining why it had "filed for reorganisation under chapter 11 of the US Bankruptcy Code" and how this "restructuring" constituted "good progress", et cetera. So these days, when a debut novel becomes the subject of a publishers' bidding war and then sells for a million dollars in the US and half a million pounds here  as with this one  there are bound to be one or two raised eyebrows.

Before we go any further, though, it's worth saying that it is entirely unfair to blame the author for the size of her advance  she has as little control over this figure as she does over the size of her sales. Such criticism is only ever naive or envious. Two legitimate questions do immediately suggest themselves, however: what did all those publishers see in The Age of Miracles and is the actual writing any good?

The answer to the first is fairly straightforward. Ostensibly, this is a novel about the gradual slowing down of the Earth's rotation as told by an 11-year-old girl from the Californian suburbs who is now turning 12. The periods of daylight and darkness grow ever longer. Faced with panic, the government quickly decides that the best plan is for everyone to live on the original 24-hour clock  "clock time"  though this means that it is no longer necessarily light in the day, nor dark at night.

"The Slowing" gets worse as the novel progresses: birds find it harder to fly, crops start to fail, whales beach, trees fall, radiation increases and random people start to suffer from a mysterious illness  "the syndrome". Meanwhile, "real timers", who refuse to abide by "clock time" and seek to live by the ever-lengthening circadian cycles, are vilified and go off to live in communes.

It is an interesting idea and, as far as I know, an original one. Readers will be intrigued. There is certain to be film interest. Publishers have bid for far worse.

The answer to the second question is more complex. Walker is a decent stylist of the keep-it-direct American school, though there are lapses: Julia misses Hanna, her best friend, "like a phantom limb".

But where Walker excels is voice. She is deft, convincing and sometimes brilliant in her evocation of a young girl's experience of complex and flawed adult relationships. Likewise, Julia's suffering at the hands of her crueller peers is skilfully done.

In other words, what we have here is a fine coming-of-age novel wrapped in a high concept. And my guess is that this book started as the former and was spliced into the latter. "This was middle school," Walker writes, "the age of miracles, the time when kids shot up"

But this splicing seems to me a shame. Because the truth is that Walker's gimmick obscures and detracts from her own talent. She doesn't really need "the Slowing" at all. In scene after scene  between Julia's mother and father, Julia and her grandfather, Julia and her piano teacher, Julia and her fellow students at the bus stop, Julia and Seth, the boy on whom she is fixated, Julia and her emotionally distant father  Walker renders her characters persuasively, with insight, economy and subtlety. Strip out the creaking contrivance and the novel's many affecting moments would surely resonate all the more through the sincerity and power of their realism.

The paradox is that without the high concept, publishers wouldn't have had the confidence to buy the novel at such a price. Indeed, Walker might not have believed she could sell it. And in this sense, The Age of Miracles is a book of our time. Would it have got all the attention, would it even have been published, if it were "merely" a beautifully observed coming-of-age story in the great American tradition? It's an awkward question. And one that Walker, a publisher herself, will have been acutely aware of.

But for this reader at least, it is mildly depressing that so nimble, delicate and emotionally sophisticated a novel should find itself burdened by such sci-fi oafishness.