When archaeologist Adrian Vale receives a mysterious invitation from a Greek antiquities dealer, he is drawn into a puzzle rooted in the final days of Constantinople.Istanbul is a city built on secrets.When archaeologist Adrian Vale receives a mysterious invitation from a Greek antiquities dealer hidden deep inside the Grand Bazaar, he is drawn into a puzzle rooted in the final days of Constantinople. At its centre lies one of the greatest unsolved mysteries of Byzantine history: the lost burial place of Constantine XI, the last emperor of the Eastern Roman Empire.The only clue is a strange symbol on an ancient medallion — a cross within a circle, marked by uneven arms and carefully placed dots.Together with Laila Mercer, Julian Cross and Emrecan, a formidable local guide who knows the forgotten layers of Istanbul better than anyone, Adrian follows a trail through old inns, vanished churches, ancient walls, Genoese cellars and buried cisterns.But in a city where every stone remembers something, some secrets were never meant to be found.And some have been protected for nearly six hundred years.