The latest Jack Howard thriller from internationally bestselling mastermind David Gibbins, who uses his real world experience as a marine archaeologist to write action-packed historical novels. AD 256 Christians are being persecuted by the Roman Emperor Valerian, who demands that all relics be turned over to him. Secretly, Pope Sixtus passes the greatest relic of them all to a follower who entrusts it to the Jewish community in Spain. 1684 Samuel Pepys has been sent to oversee the evacuation of the English colony of Tangier, in the face of threats from Moors and Barbary pirates. Officially his job is to compensate the colonists for their losses. Unofficially, he is there to attempt to retrieve an incredible treasure that has resurfaced after more than a thousand years. Present-day Jack Howard and his team are excavating a 17th-century shipwreck off Cornwall in England. Jack realizes that the wrecked cargo contains clues to an ancient mystery. In a quest that brings him to a deadly confrontation with the present-day inheritors of the Inquisition, he goes to North Africa, to Portugal, and across the Atlantic to the sunken ruins of the pirate city of Port Royal in Jamaica, and then to a 17th-century silver mine that becomes a descent into Hell itself--all in the search for the greatest lost treasure of Christendom--the fabled Holy Grail.