Salmon Fishing in the Yemen, by Paul Torday

At the centre of Paul Torday's debut novel is an unlikely hero, Dr Alfred Jones, a humble civil servant at the National Centre for Fisheries Excellence. A shy boffin, he is more at home researching the mating habits of freshwater mussels than wondering why his marriage has become a loveless bore, and why his chilly financier wife Mary has seized the chance to work abroad. When a rich Yemeni potentate, Sheikh Muhammud, offers to fund a scheme to populate the wadis of his desert lands with Scottish salmon, Jones's first instinct is to dismiss it as ludicrous.

But he has reckoned without the Foreign Office and its keenness to spend the sheikh's money. Miles above his innocent head, interdepartmental memos start to fly. A chain of spin doctoring leads all the way to the prime minister, who is delighted to support any Middle East initiative that involves no dying soldiers. The scheme starts to take on a life of its own and Dr Jones is the only character who knows how it might actually be achieved. Everyone else is in for the cash, the kudos or the job security.

He has, however, two allies. One is the sheikh himself, a well-evoked figure with a visionary fondness for his hobby ("there is one group of people who in their passion for the sport ignore all things to do with class. The sayyid and the nukka are united and stand together on the riverbank and speak freely without restraint... Of course I speak of salmon fishermen"). The other is Harriet Chetwode-Talbot, a posh factotum of the sheikh's, with an army fiancé stationed in Iraq. Together they set out to make the sheikh's dream a reality.

The narrative swims along in a shoal of letters, e-mails, interview transcripts, newspaper articles and similar metafictional games. They range from editorials in Trout & Stream and entries in Hansard to exchanges between al-Qa'ida operatives bent on killing the sheikh for contravening sharia law. Gradually the author's moral focus becomes clearer: this is a battle between cynicism and belief.

Dr Jones, Harriet and the sheikh represent an oasis of can-do idealism in a desert of ignorance, attitude-striking and rapacity, as embodied in the book's villain, Peter Maxwell. Maxwell is director of communications to the PM, Jay Vent, and could not be more closely drawn from life if he had "Alastair Campbell" tattooed on his forehead. Torday clearly dislikes this unelected power-broker but seems genuinely interested in his cast of mind. He lets him take over large chunks of narrative, until his voice (pragmatic, self-important, self-deluding) threatens to overwhelm Jones's direct, awestruck response to the Yemen landscape and his own awakening sense of belief.

This is a book of considerable charm, an echo-chamber of a dozen different voices adroitly ventriloquised. It's also staggeringly old-fashioned. Torday's imagination, though vivid, seems stuck in elderly movies. Alfred Jones is a classic little-man-against-the-system from the Ealing comedies. The wise, benign sheikh is Herbert Lom in a turban. The posh, fragrant Harriet is pure Virginia McKenna (until she tells him that his enthusiasm makes him look boyish, which is of course Celia Johnson in Brief Encounter). There's even a foggily discreet did-they-don't-they love scene that's from another century (the 19th).

But just when you're upbraiding Torday for his valetudinarian decency, he pulls off an ending both apocalyptic and wholly unexpected. His book turns out to be a moral tale about the importance of believing in something, and the comparative unimportance of everything else. Fishermen will love it. Non-fishing readers will find it enjoyable, faintly moth-eaten and oddly thought-provoking.