Richard Gaunt is one of those lucky narrators with a happy gift for stumbling across adventure. Mind you, his is a peculiarly meandering stumble. It starts in a Mayfair gambling den, where Richard, a former army officer down on his uppers, wins a much-needed few thousand quid and accepts a double-or-quits wager that he won't be able to walk to Oxford for lunch at the Randolph Hotel in 11 hours' time. He sets off and has just yomped beyond Stokenchurch when he is suddenly attacked and bundled into the back of a Range Rover. He comes to in a plush country house. Here he meets a smooth but mysterious cove called Mr Khan who gives him his second proposal  this time of marriage, to a beautiful Afghan woman called Adeena, for which he'll be paid £10,000. All this by page 26.

Now that the plot's properly under way, it settles into a more conventional pace, helped by a structure in which the present day is intercut with scenes from Gaunt's back story  black ops tour in Iraq, tour in Afghanistan that ended in a roadside ambush, inability to adjust back home, disastrous attempt to run a restaurant with his girlfriend, down on his uppers, pays a visit to that gambling den in Mayfair . . .

The plot itself sees our hero get married to the clearly reluctant and oppressed Adeena, before he rediscovers his morality and escapes with his accidental bride, first up north to a chum's ancestral pile and then back down to his grimy flat in London. Meanwhile a chum of a chum of a chum in the security services tips him the wink that they're very interested in Mr Khan, and soon Richard's involved in another hunt, to stop an al-Qaida outrage.

The out-and-out thriller plot is a departure for Torday, but his many fans will find themselves in a familiar and distinctive milieu  middle-to-upper class and rooted in the north of England (here with sorties to London and Oxfordshire). Indeed, there's a cameo appearance by Eck Chetwode-Talbot, who was related to the love-interest in Salmon Fishing in the Yemen and narrated Torday's fourth novel, The Hopeless Life of Charlie Summers, which also featured the mysterious Mr Khan.

Torday has now published five novels in as many years since making his debut at the age of 60, and there are obvious traces of the smoke from his keyboard here, mainly in the style, which is workmanlike and sometimes dull. Likewise, the plot is serviceable rather than brilliant  there's that odd false start with the wager, and quite a few scenes, especially those set in the gambling den and country house, are strangely reminiscent of low-budget 1970s telly. Some aspects bring to mind the even more venerable exploits of John Buchan's Richard Hannay.

But there are good reasons why Torday has found success, as this novel also shows. There's real substance to the characterisation, at least of the principals, and a keenness to incorporate the dark and the serious (here, as before, supplied by the conflicts in Iraq and Afghanistan) and to engage with contemporary politics and issues (ditto). Above all, there's his desire to entertain and to keep his readers turning those pages.

Decent enough plot, well-drawn main characters, thoughtful structuring, contemporary setting, engagement with the major news stories of our time  these may not seem remarkable qualities but there really aren't many middlebrow writers providing them at the moment. For all his genre-hopping, Torday is Mr Reliably Readable  with a little something extra for fans of Northumberland's upper class.

Harry Ritchie's The Third Party is published by Hodder.