The incomparable Leonardo da Vinci had great plans for the magic Sphinx Emerald - but though the King of France was his friend, he had also made a bitter enemy. Written by Henry James O'Brien Bedford-Jones (April 29, 1887 - May 6, 1949) who was a Canadian-American historical, adventure fantasy, science fiction, crime and Western writer and who became a naturalized United States citizen in 1908.