NICOLA BARKER'S novels and stories are populated by characters who get intensely irritated with each other. Early in Darkmans (third in a series of "visionary narratives of the Thames Gateway"), a man named Kane gets annoyed with Elen, a chiropodist. What upsets him is that she mocks the way he uses his mobile phone, prompting him to imagine that she lives "without technology, without chatter".

Darkmans, like much of Barker's fiction, is all about chatter. Her characters launch into aggressive conversation as they meet, and in their anger and frustration resemble characters from drama as much as literature, refugees from Mamet or Pinter. This chatter is amplified by Barker's digressive, gossipy authorial voice, which prevents the reader from feeling any distance. There is a constant sense she might launch us into the mind of one of her psychotics and leave us there, and this gives her books a fearsome energy.

Darkmans is one of her most challenging novels. As with Behindlings, hundreds of pages pass with little or no dramatic incident. Gradually, a theme emerges: the impact of the past on the present, and how the modern novel or town cannot afford to ignore history.

A woman named Peta Borough argues that modern life has become medieval. She connects the modern obsession with gratuitous consumption to medieval feasts and that "courtly love" literature is mirrored by the popularity of sequences such as Harry Potter and Star Wars.

Barker's character believes the locus of change is language, with several plays on the way that text-speak and pop-culture references resemble the mutability of medieval spelling.

Barker's interest in sociolinguistics has long been part of her fiction, but here this concern is central to the plot.

Barker pursues many other interests, including chiropody, scratchcards, sex, dogs, gardening, religion, cars and class. Although her characters, on the whole, travel only small physical distances, they constantly make mental connections back and forth in time and space, living in fear of psychic forces that seem to lead to the "darkmans" of the title.

Her characters' desperate search for meaning is revealed to be as pointless as public interest in Harry Potter. And she thumbs her nose at readers of literary fiction by questioning the value of her own novel, which seems cruel. But I suspect Barker knows exactly how essential her own work is.