NEW YORK - The promotion for Dan Brown's new thriller will itself be a bit of a puzzle.

Publisher Doubleday announced July 7 that Brown's "The Lost Symbol" - his first novel since "The Da Vinci Code" - will be preceded by a summer-long procession of "codes, cryptic trivia, puzzles, secret history, maps, aphorisms" and other daily teasers on Facebook and Twitter.

The book, which comes out in the fall, will be set in Washington, D.C., and will feature "Da Vinci Code" protagonist Robert Langdon, again caught up in secret societies and hidden codes.

"The Da Vinci Code," released in 2003, has more than 80 million copies in print worldwide.

"The Lost Symbol" has an announced first printing of 5 million.