Interview: Owen Sheers says Second World War plans for a British resistance provided inspiration for his debut novel

If the Normandy landings had been repelled and the German army had invaded Britain, thousands of ordinary men would have gone underground to join a resistance force. The plans were laid and the bunkers were dug: the insurgents would have tracked and attacked Nazi troops, sabotaged transport lines and killed collaborators. This vision of an occupied Britain forms the backdrop to Resistance, the compelling debut novel by the young Welsh poet and playwright Owen Sheers.

Such counter-factual Second World War territory has been well trodden by authors such as Philip Roth (The Plot Against America) and Robert Harris (Fatherland). Sheers chooses to set his story not amid military manoeuvres or Cabinet room negotiations, but in a tiny Welsh border community. One morning the farm women wake up in empty beds - their husbands have vanished, presumably to join the resistance movement. Then a German patrol arrives, on a special mission to find a stashed historical artefact, and is snowed in for the long winter of 1944. The two groups must rely on each other to survive, as the story probes the nature of absence, occupation, collaboration and personal resistance.

"Stalin was within minutes of abandoning Moscow, and the Arctic convoys could have easily failed," Sheers says. "Huge historical events can turn on one person." He studs the story with details from this alternative world: Churchill exhorts his fellow countrymen to " perish in the common ruin rather than fail or falter in your duty" and promptly flees to Canada; the BBC reports how Nelson's Column has been shipped to Berlin; Germany declares that "British authorities may continue to function if they maintain a correct attitude" (part of a real order issued to senior Wehrmacht officers in September 1940).

But Sheers is uncomfortable with the counter-factual tag. "This is an alternative, imagined story; it's retrospective science fiction." That's why he rejected the conventional choice of 1940-41 as the war's turning point: "An invasion in 1941 would have been blitzkrieg, and it was more important to have a realistic psychological and emotional situation. These soldiers are at the end of a long war of attrition, they have been brutalised, and they are presented with an opportunity where their survival depends on a fragile mutual dependency."

These themes also run through Sheers' poetry. Since his attention-grabbing debut The Blue Book was shortlisted for the Forward Prize Best First Collection in 2001, he has borne the weight of expectation: being tipped by Poet Laureate Andrew Motion and named as a "Next Generation Poet" by the Poetry Book Society. The Independent on Sunday tipped him as one of the 20 best young British writers in 2001. But he's obviously not fazed by the pressure: his travelogue The Dust Diaries, in which he retraced the steps of a missionary ancestor through Zimbabwe, was shortlisted for the Royal Society of Literature Ondaatje Prize and won the Welsh Book of the Year Award 2005. Last year brought a second volume of poetry, Skirrid Hill, which won critical plaudits for its depth, maturity and vision.

Poetry has always been in his blood - "it feels like a valid way to interpret whatever I do" - but at school he was far from withdrawn, entering writing competitions while captaining the rugby side and competing in pentathalons. He brings a poet's craftsmanship to Resistance, but the rhythmic sentences serve a driving storyline as the fate of both occupier and occupied hangs in the balance. His model was Grahame Greene's The End of the Affair, which he hails as "perfectly crafted - you can read it in a few hours". The pacey, scenic chapters show his scriptwriting experience (the Old Vic and Joseph Fiennes are currently developing his one-man play about the overlooked Second World War poet Keith Douglas).

Though there is only the lightest Welsh inflection in his clipped RP tones, Sheers grew up in Abergavenny on the edge of the Black Mountains, and returned frequently to research the novel. "I suddenly realised that I wanted to write against a landscape that I know. I set out to capture the language of the farming community, and also the unspoken language of those hills." The book revels in the lilting vowels of the Olchon valley women, as well as the raw bloody physicality of farm life.

There were real plans for a British resistance force: by 1940 dozens of networks had been recruited and trained. Sheers first picked up the story from a local builder, when he was lifting slate as a summer job. "I was fascinated by the idea that as a vital tactical tool the nation would fall back on people who knew the land." Then in 2001 - on the morning of 9 September - he heard a Today programme interview with George Vater, who as a young man had been recruited into the Auxiliary Units Special Duties section: a web of Abergavenny locals who would spy on occupying troops. "He said that he'd been told to expect a 'full lifetime' of 14 days [after an invasion], and something in the tone of his voice suggested a massive gulf between his generation and ours."

Sheers knew Vater, who farmed near his parents' house in Llanddewi Rhydderch and had recruited him for Pontypool rugby club. He visited him, and was shown the sheet of German military insignia that Vater's recruiter had handed him to learn. This was fertile ground for fiction, with obvious contemporary resonance. "I was especially interested in the absolute secrecy - this incredible idea that wives and parents would not know, and what that would do to an isolated community." Sheers imagined these abandoned wives, as the weight of absence bears down on them. What would happen if they were joined by a brutalised band of German soldiers? " Suddenly you have a situation of occupation: two disparate groups are forced into a fragile harmony, and start to lead themselves down paths away from war. But the course has been set."

The sheer-sided Welsh border valleys have appealed to various groups trying to extract themselves from the flow of the world: from 11th-century monks to typographer Eric Gill's artistic community in the 1920s (one of Gill's residents was the poet David Jones, who has a cameo role in the novel). The severe conditions Sheers depicts are based on the winter of 1947, when farmers founds herds of ponies frozen together under snowdrifts, and sheep ate the wool off each others' backs to survive.

The lead characters are Sarah, desperately clinging to the hope that her husband will return, and Albrecht, a Bach-loving, sympathetic German captain who is plotting an escape from the war and his own dark deeds. Both are wrestling with their desires, their consciences, and their own histories. As their relationship unfolds, the outside world looms ever closer , and they must decide whether to elope or fight. "Can you extract yourself from the past, from what you've done, from the situation you've been in?" asks Sheers. "I wanted the book to focus down to the final scene where Sarah and Albrecht have to make final choices, and face up to their different kinds of personal resistance."

The extract: Resistance by Owen Sheers (Faber £14.99)

'It was The Court that made her sure. Every man in the valley had gone. Last night there were seven of them here. With their pipes and their cigarettes, with their caps, their boots, their rare laughter, their wind-weathered faces and their earth-hardened hands. But this morning there were none. It was as if the valley had experienced its very own Passover and they, the women, had some how been left untouched by whatever dark angel had visited in the night and taken their men.'

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