One happy aspect of Lionel Shriver’s peek into the near future (the novel opens in 2029) is the number of unusually rounded elderly characters she presents. Her pitiless eye notes every mark of age and vanity in the older generation of the Mandible family, but they remain in robust health, sharp without being merely spry, and full of personality. They have too much life as far as the younger family members are concerned, waiting impatiently for the wealth to trickle downwards.

Jayne and Carter, already in their sixties, will be disappointed, for Shriver’s doomsday scenario concerns a catastrophic devaluation of the dollar which wipes out the family fortune overnight. The Mandibles descend the social order rapidly, along with everyone else in the United States. It’s a short step from dinner parties to dumpster diving as the American dream goes bust.

Shriver articulates a fierce resentment of the Boomer generation, who will be the least inconvenienced by the turmoil; they had it good for most of their lives, after all. Her future America is both horribly plausible and slyly amusing. Mexico is on the rise and the US president is Latino. There has been a Chelsea Clinton administration, phones and tablets have been replaced by a cloth-resembling folding device called a FleX that people have been known to mistake for a tissue, and the latest bafflingly trendy cuisine in New York is Canadian: ‘The city’s elite was running out of new ethnicities whose food could become fashionable.’ First there’s a run on extra virgin olive oil; then cabbages cost $20; soon there isn’t any toilet paper to be had, and eventually lawlessness reigns.

Jayne and Carter’s two daughters, Avery, married to Lowell, a pontificating economics professor, and the less well-off, more practical Florence, anchor the tale, though Florence’s son Willing becomes its main focus and hero. Wise beyond his years, he easily sees through the adults’ fantasy that this is a mere blip. Through the character of Nollie, a septuagenarian novelist, Shriver rails at the future prospects for professional writers trapped between pirates and amateurs.

The Mandibles are all chatty, articulate types, but much of the dialogue comes in the form of ungainly slabs of financial exposition. At Avery and Lowell’s final dinner party, the guests take turns to deliver crushing weights of analysis. Even the kids are in on it:

‘The dollar is a historied currency that’s stabilised the international economy for over a century.’

‘Historied? The dollar’s history is of becoming systematically worthless.’

That’s a 14-year-old and a 16-year-old talking.

The effect is rather as though Dickens, instead of dramatising the plight of the hapless Court of Chancery litigators, chose instead to have the characters of Bleak House sit around endlessly discussing the iniquities of the legal system. Not that Shriver doesn’t have some stand-out scenes, especially when civilisation goes feral; it’s just that the exposition far outweighs the action. Her intricately constructed modelling is as intellectually impressive as it is dramatically inert. If only they’d leave off their prating and kill each other, you find yourself wishing.

For all that, The Mandibles is a scary, depressing and convincing horror story, akin to reading about teetering on the edge of a precipice while actually teetering on the edge of a precipice. Start stockpiling the tins.