“But that was all years ago now,” we’re told in Austin Duffy’s novel Cross, set in 1990s Northern Ireland, “and at some point you have to get on with things.” This pragmatic forgetting has not, to put it gently, been a traditional feature of politics in the north, where there is still an annual public holiday – only last week on 12 July – celebrating a battle that took place in the 17th century.

Still, since the Good Friday agreement of 1998 baked the principle of “I may forgive but I’ll never forget” into constitutional politics, peace has broken out, and given the transformation in Northern Ireland since then, it’s surprising the period hasn’t had more attention in fiction.

Step forward Dublin-based writer Duffy, whose fourth novel is set in the fictional border town of Cross at the time of the IRA’s 1994 ceasefire. The narrative cycles around the key characters, beginning with Francie, an elder figure in what we might call the terrorist community. “Francie just knew things,” goes the refrain; he’s an old-fashioned republican who sees his cause as a job, unlike his teenage sidekicks Kaja and Mickey, who are excited at their involvement in the murder of a policeman.

Then there is Nailer – so called because he once nailed a man to the floor – and Handy Byrne, “hardcore local republican legend” and a bit of a psychopath. There are women too: Cathy Murphy, the daughter of a police informer or tout – the worst crime of all in criminal circles – and the Widow Donnelly, who unnerves the hardmen with her constant presence sitting on an upturned drinks crate in the town square in protest for her missing son.

In the repetitive cycle of history represented by people such as Francie, the narrative is somewhat circular to begin with – exchanges and threats and gambits going nowhere – but then a new figure arrives. This is MOC, a prominent republican politician from Belfast, who comes to Cross to sell the imminent ceasefire to the foot soldiers. “It’s not like we’re going away or anything,” MOC assures them, in case he wasn’t a clear enough analogue for Gerry “They haven’t gone away, you know” Adams.

But old habits die hard and there’s some sickening – and, in readerly terms, satisfying – nastiness in Cross, from bloody killing to drink-spiking and its consequences (“[he gave] it a big stir with his famous trigger finger”). And even the hardmen such as Byrne have harder men above them, such as Casio and Drill Bit, who might have answers to Donnelly’s questions about her missing son, and whose idea of republican culture, far removed from Francie’s Marxist politics, is watching back-to-back Jean-Claude Van Damme films.

Cross portrays a world of utter corruption, where the cause begins to be forgotten, swept away in the wake of power that violence bestows; violence that ultimately turns in on itself. It is a striking exhibition too of a male-dominated society, where the men use weapons and the women, defined by the men they mourn, seek expression through words and silence.

And it’s a strange book that describes this strange world. As a realist novel, Cross doesn’t entirely work: the dialogue can be stagey, some characters (such as Nailer and Byrne) aren’t well distinguished and plausibility is strained when Nailer waxes philosophical about the works of Edward Gibbon. But it fits together as a representation of a time and a culture, where the people are less characters than archetypes and surreal symbols deliver emotional meaning: the appearance of a flamingo in the town, replaced later by a “plague” of crows; the sinister sight of a mountain on fire.

In this dreamlike oddness, Cross is reminiscent of Anna Burns’s Milkman, though Duffy shies away from the intensity of that book’s compact style in favour of a shifting register. He switches between blunt dialogue, stream-of-consciousness and a choral narrative in the first-person plural. These shifts give the story a jittery, uncertain feel, the sense of a narrative and a world in danger of breaking down – just like the fragile peace the story ushers in.

• Cross by Austin Duffy is published by Granta (£14.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply