What did Arthur Conan Doyle mean by that now infamous remark, uttered towards the very end of his life, that the only Sherlock Holmes story with the power to intrigue him was ‘The Adventure of the Second Wife’? For there was no such story.

It falls to an unlikely pair - a London doctor and a literature professor from Istanbul - to unravel the clues to this puzzling mystery, clues that lie buried in the stories of their own families and lead back to the fin-de-siecle court of Abdulhamid II, the last Ottoman ruler to command the world stage.

Historians write of the Sultan’s addiction to Sherlock Holmes. He would even have the stories read to him as he lay in bed at night - an obsession (it is now safe to reveal) that was to save his life and alter the course of a dying empire. But solving one mystery can mean disturbing other, darker secrets, such as the real story of ‘The Second Wife’.