Criticism of The Da Vinci Code "Smithy Code Jackie Fisher who are you Dreadnought", referring to the British admiral whom Judge Smith admires. As with the book, this secret message made use of Fibonacci numbers for its encoding. Dan Brown has been sued twice in The United States by author Jack Dunn who claims Dan Brown copied his book The Vatican Boys (1997) to create The Da Vinci Code, Angels & Demons and Brown's now famous character Robert Langdon. Jack Dunn calls Dan Brown's actions, "The Largest Literary and Movie Crime in History." At a conference on April 28, 2006 Archbishop Angelo Amato, the secretary of
The Da Vinci Code mathematical message written beside his body and a pentagram drawn on his chest in his own blood. The novel explores an alternative religious history, whose central plot point is that the Merovingian kings of France were descended from the bloodline of Jesus Christ and Mary Magdalene, ideas derived from Clive Prince's "The Templar Revelation" (1997) and books by Margaret Starbird. The book also refers to "The Holy Blood and the Holy Grail" (1982) though Dan Brown has stated that it was not used as research material. "The Da Vinci Code" provoked a popular interest in speculation concerning the Holy Grail