Langley, Va...........CIA hq......................actually............Langley was the 3rd sec. of the SI............oh boy.............

Brown's third novel featuring Robert Langdon, The Lost Symbol, was released on September 15, 2009.^[18] According to the publisher, on its first day the book sold over one million in hardcover and e-book versions in the US, the UK and Canada, prompting the printing of 600,000 hardcover copies in addition to the five million first printing.^[19] The story takes place in Washington D.C. over a period of 12 hours, and features the Freemasons. Brown's promotional website states that puzzles hidden in the book jacket of The Da Vinci Code, including two references to the Kryptos sculpture at CIA Headquarters in Langley, Virginia, give hints about the sequel. This repeats a theme from some of Brown's earlier work.^{[citation needed]}

Brown's fourth novel featuring Robert Langdon, Inferno is a mystery thriller novel released on May 14, 2013, by Doubleday.^[20] It immediately became a bestseller.^[21]