When his business partner and best friend is brutally murdered, callously beheaded by apparent Muslim extremists in a cellar beneath the historic Hagia Sophia museum in Istanbul, Anglo-American scientist Sean Ryan flies to Turkey intent on finding out why Alex died so horribly.

Within hours of his arrival he finds himself on the run, pursued by armed thugs intent on killing him too.

He is rescued by Isabel Sharp, a member of staff at the British Embassy, whom he soon realises does a lot more than help tourists who have had their passports and money stolen.

Sean and Isabel realise that his friend Alex had inadvertently stumbled on evidence of a terrifying conspiracy that threatens death and destruction, not just in the ancient and beautiful city of Istanbul, but on an international scale.

As stop-at-nothing terrorists prepare to unleash a deadly virus, the couple find themselves in a break-neck race against time to unravel the clues Alex left to prevent tragedy on a vast scale.

Dubliner Laurence O'Bryan's compelling debut thriller combines plenty of stirring action with fascinating historical detail about a city and a country he quite obviously loves.

And how O'Bryan has cracked the thriller market with The Istanbul Puzzle and the route to its publication by Avon, a HarperCollins imprint, is an interesting story in itself.

The manuscript was discovered on a website called authonomy.com set up a few years ago by HarperCollins. The website encourages budding authors to upload their stories and books where they can be read and, crucially, rated by their peers, authonomy's 100,000 or so members.

The more positive the reviews a book gets, the higher it rises in the digital 'charts' and the more likely one of HarperCollins' editorial staff is to read it and consider it for publication.

O'Bryan is the second writer to have been selected for traditional publication by HarperCollins through this method of selection. Penguin has a similar site, bookcountry.com.