The unreliable narrator has a long and distinguished history, from Nabokov's self-justifying Humbert Humbert to Agatha Christie's first-person killer in The Murder of Roger Ackroyd. At its best, the device forces an uneasy twinge of sympathy and a moral ambivalence towards even the most depraved of characters.

Ross Raisin's antihero Sam Marsdyke is a classic of the genre. A gangling, 19-year-old misfit who works on his father's sheep farm on the West Yorkshire moors, Sam was expelled from school for some unexplained trouble with a girl. He is an outsider, a scowling oddball shunned by society, who finds comfort in the natural world. His closest companion is a sheepdog puppy named Sal and he is capable of an empathy with animals that is lacking from his human interactions.

But the landscape for which he feels such affinity is under siege from out-of-towners: from gastropub chains, second-homers and bobble-hatted ramblers with their foil-wrapped sandwiches. The sense of physical encroachment is pervasive and claustrophobic, mirroring Sam's growing mental isolation.

He develops an obsession with Josephine, the teenage daughter of a middle-class family newly arrived from London. She sees in Sam a chance to rebel against her ghastly mother and the two abscond across the moors. But is this really the romantic elopement Sam seems to imagine or is there a more malign undertow?

This uncertainty makes God's Own Country a compelling debut novel, its sinister narrative shot through with flashes of black humour. Raisin writes with such a sureness of touch that Sam is always credible, even at his most unlikable. His voice is entirely original, laced with Yorkshire dialect and possessed of an easy, almost casual descriptive power: "a giant shadow spread over the Moors, turning them russet to dark brown, like a mighty beer stain soaking through the carpet". The result is engrossing and unsettling; a rich, sticky hotpot of a book with a lingering aftertaste of disquiet.