London, 1892: Private enquiry agents Cyrus Barker and Thomas Llewelyn are directed to an underground tunnel leading to Downing Street, in this 11th outing, after Blood Is Blood. After an agent is killed, the Prime Minister dispatches Barker to retrieve a satchel containing a first century gospel owned by the Vatican. The German government wants to get possession of it, but so do secret societies, government assassins, political groups, and shadowy figures. As all of them converge on the holy relic, the case could be beyond even the prodigious talents of Cyrus Barker.