Author Dan Brown to adapt The Lost Symbol for the big screen… Author Dan Brown has confirmed that he will write the screenplay adaptation of his book The Lost Symbol. In The Lost Symbol, Robert Langdon, the protagonist of both The Da Vinci Code and Angels and Demons, faces off against the Freemasons in Washington DC. This is the first time that Brown has adapted one of his own novels. As of yet, it is not known if Tom Hanks will return as Langdon. The Lost Symbol hits theatres in 2013.