They have been drawn into a plot more insidious than anything they could have imagined—a battle to control one of religion’s greatest secrets. For English detective Nigel Lyman, it begins with the suspicious suicide of a corrupt Italian banker in London. For French-born Mariane Soury-Fontaine, it starts with the mysterious disappearance of her lover. And for American mathematician Joseph Koster, the search leads through France’s soaring cathedrals to the baffling labyrinths that masons once carefully inscribed in their floors.

These strangers are about to crack a code that dozens have died for, a puzzle whose power reaches back to the birth of the Christian faith, through the echoing halls of the Vatican, and to the dark, corrupt realms of organized crime. Now staying alive is the ultimate challenge. Because the next revelation is the most forbidden of all . . .