The Flame Alphabet By Ben Marcus Granta, £16.99

Ben Marcus’s new novel comes garlanded with praise from, among others, Tom McCarthy, whose C shares a similar dark imagination, avant-garde sensibility and fascination with rudimentary technology.

Marcus is a champion of experimental fiction, the kind you might have to read twice to really understand and that might or might not be worth it. Famously, he got into a minor literary fracas with Jonathan Franzen, author of The Corrections, via the pages of Harper’s magazine, in which Marcus stoutly defended the “difficult”, experimental novel (no one understood Ulysses either, goes the argument, and many still don’t, but that doesn’t mean it’s no good), and Franzen maintained that Marcus and his highbrow posse were accelerating the demise of a form already under serious threat from other media.

What would happen to humans if we could no longer communicate directly? In Marcus’s “intellectual horror story” an epidemic has hit the US, making the speech of children toxic to adults, who fall horribly ill and eventually die from listening to their offspring. Parents, including the narrator, Sam, and his wife, Claire, are forced to flee their homes and go into hiding while their children are rounded up and interned in quarantine areas.

The outbreak seems somehow connected to a secret, esoteric Jewish sect, which transmits its religious services via an underground cable network that can be accessed through listening devices such as the one in the hillside hut where Sam and Claire had gone to “worship” every week.

Sam goes to work in a research lab, where he tries to find out what it is in language that has suddenly become so lethal. It turns out that written words, too, are toxic to adults – but at what point does the poison kick in? Sam uses a variation of the pinhole device, which allows him to see only a part of each letter at a time. He tries a variety of alphabets, both ancient and modern, including cuneiform. He tries removing the vowels and writing in all kinds of materials, including smoke, but still his research subjects – “language martyrs” – get sicker.

And it’s not just language. In the lab, “Gesture was tested, mostly on the sick, to see how rapidly they would expire if exposed to unceasing and explicit mime.” As the epidemic worsens, all methods of human communication become a health hazard.

Sam tries to invent a new way of transmitting meaning, conscious always of the fact that his and Claire’s teenage daughter, Esther, will one day soon become an adult and so susceptible to the virus herself.

It’s a sci-fi disaster-movie plot with a determinedly cerebral twist. Marcus offers a vividly realised dystopia, and it’s an impressive feat of imagination (and, of course, language), though at times the weirdness seems to clash a little with the traditional, pro-family theme. The villain/s, called variously Murphy and LeBov (we’re never sure if they are the same person), are less than convincing. Allusions abound to arcane aspects of Judaism, Aesop’s fables and more.

This malevolent, silenced world is full of strange substances. There are the fetid fluids that leak from the bodies of the stricken (often increased rather than stemmed by attempted cures); the serum extracted from live children that, when injected into adults, gives them temporary immunity; a strange pink gel that, when spread on bits of bark, then heated and chewed, gives Sam enough sustenance to survive without food or water for long periods. And there is the “salt” that covers the now deserted countryside – the residue of language.

For all this visceral imagery, The Flame Alphabet is unnervingly bloodless in tone. The narrator, Sam, relates the “facts” of the story with a chilly detachment. His attitude to his wife is ambivalent, his attitude to others’ suffering indifferent. Maybe he can’t afford compassion, but you do at times long for a joke or two (that crack about mime isn’t enough). After all, isn’t Beckett’s black humour one of his virtues?

Still, jump in if you want your brain stimulated. Just don't expect to have your cockles warmed. Detach and survive. Easy as ABC. CATHY DILLON

Peaches for Monsieur le Curé

By Joanne Harris

Doubleday, £13.99

You cannot blame Joanne Harris for revisiting her most successful book, Chocolat. Twice. The Whitbread-shortlisted novel, about a chocolatier who peps up Lent in a French village with her sinful confections, seduced millions of readers and was made into an Oscar-nominated film.

In this book, the third featuring the chocolate-making Vianne Rocher, Harris returns to Lansquenet, and this time it’s Ramadan. August 2010, to be precise, shortly before the French government banned the wearing of the Islamic veil.

Much has changed in the intervening eight years. Whereas Chocolat was concerned with feasting and fasting, Peaches for Monsieur le Curé is all about cultural clashes. A Muslim community has rooted itself along the banks of the river in Lansquenet, an intensely Catholic village. There is a mosque with an imam and women veiled from head to foot. The Muslims have brought new ways, and conflict is brewing. Even the more open-minded villagers are feeling the tension. “I’m sick of trying to be sensitive,” snaps Vianne’s friend Josephine, who feels she is being judged because her cafe serves alcohol.

Vianne again encounters Fr Reynaud, the overzealous curate from Chocolat, who is suspected of serious offences and has been ordered to step down. Adding insult to injury, the bishop has replaced him with a priest who likes to use PowerPoint during sermons and has, quelle horreur, bleached teeth. It is up to Vianne, who has magical powers, to sort everything.

And so, in Lansquenet, it’s the Islamic crescent moon versus the Christian cross, with the sound of the azan, the traditional call to prayer, competing for supremacy with the church bells. This is one small village, but of course the religious conflicts are universal ones. Harris is good at tackling tricky issues, and she doesn’t shy away from the problems of the face veil. “How do you even start to talk to someone who never shows their face?” a villager asks in exasperation.

The book is thought-provoking, but the symbolism is heavy-handed and the melodrama relentless. It's not nearly as engaging as the original – and, sadly, there's much less chocolate. MAURA O'KIELY