Milan, 1497: Leonardo da Vinci is completing his masterpiece, The Last Supper. Pope Alexander VI is determined to execute him after realizing that the painting contains clues to a baffling -- and blasphemous -- message, which he is determined to decode. The Holy Grail and the Eucharistic Bread are missing, there is no meat on the table and, shockingly, the apostles are portraits of well-known heretics -- none of them depicted with halos. And why has...