In 1982, Italian financier Roberto Calvi, known as "God's Banker," was discovered hanging under London's Blackfriars Bridge. What wasn't found was the briefcase he was known to have had with him the night before, reportedly stuffed with incriminating documents, a special key, and a computer disk filled with codes, which together unlock a piece of the Vatican's troubled past. When the briefcase mysteriously reappears in the Vatican...