premise: Dan Brown wrote a book.
hypothesis: Daniel Gerhard `` Dan '' Brown ( born June 22 , 1964 ) is an American author of thriller fiction who wrote the 2003 bestselling novel The Da Vinci Code . Brown 's novels are treasure hunts set in a 24-hour period , and feature the recurring themes of cryptography , keys , symbols , codes , and conspiracy theories . His books have been translated into 52 languages , and as of 2012 , sold over 200 million copies . 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 . '' Inferno is a 2013 mystery thriller novel by American author Dan Brown and the fourth book in his Robert Langdon series , following Angels & Demons , The Da Vinci Code and The Lost Symbol .