EXPERTS claim to have cracked the secret behind the success of all-time best-selling novelist Agatha Christie.
And they say they are a step closer to working out a mathematical formula for what makes a book "unputdownable".
According to a study, Christie uses literary techniques mirroring those employed by hypnotherapists and psychologists, which have a mesmeric effect on readers. It could mean the structure of her novels creates physiochemical responses which cause people to seek them out again and again.
The study was carried out by linguistics experts at Warwick, Birmingham and London universities and the results are to be revealed in an ITV1 documentary on 27 December.
Dr Roland Kapferer, the project's leader, said: "It is extraordinary just how timeless and popular Agatha Christie's books remain. These initial findings indicate that there is a mathematical formula that accounts for her success."