As the blood of martyred Christians runs through Rome’s catacombs, Pope Sixtus entrusts their most sacred object to a devoted follower. Soon after, the Holy Grail disappears into the darkness of time. While overseeing the evacuation of the English colony of Tangier, Samuel Pepys attempts to retrieve a treasure which has resurfaced after more than a thousand years. Meanwhile, a Jewish merchant is tortured by the Altamanus, a secret group determined to locate the Grail. A wreck off the Cornish coast reveals clues to a mystery that marine archaeologist Jack Howard had thought beyond solving. He embarks on an epic quest that takes him to the sunken ruins of the pirate city of Port Royal in Jamaica. But the specter of the deadly Inquisition dogs his every step, and Jack must face a descent into hell itself if he is to uncover the greatest reward in Christendom.