Daniel Gerhard Brown (born June 22, 1964) is an American author of thriller novels, most notably the Robert Langdon stories: Angels & Demons (2000), The Da Vinci Code (2003), The Lost Symbol (2009), Inferno (2013) and Origin (2017). His novels are treasure hunts set in a 24-hour period, and feature the recurring themes of cryptography, keys, symbols, codes, art, and conspiracy theories. His books have been translated into 56 languages, and as of 2012, sold over 200 million copies. Three of them, Angels & Demons (2000), The Da Vinci Code (2003) and Inferno (2013) have been adapted into films. Brown's novels that feature the lead character, Langdon, also include historical themes and Christianity as motifs, and have generated controversy. Brown states on his website that his books are not anti-Christian, though he is on a 'constant spiritual journey' himself, and says that his book The Da Vinci Code is simply "an entertaining story that promotes spiritual discussion and debate" and suggests that the book may be used "as a positive catalyst for introspection and exploration of our faith".