Author Dan Brown is moving to Washington DC for the follow-up to his successful conspiracy theory novel The Da Vinci Code, publisher Random House said on Wednesday.

Brown's latest novel, The Lost Symbol, will be released on Sept 15 and again features the fictional, mystery-solving Harvard symbologist Robert Langdon, with the story taking place over a 12-hour period.

The location and plot of the book have been kept under wraps until the publisher released two jackets for the book on Wednesday at the start of a promotion campaign that includes online puzzles and codes.

Brown's US editor Jason Kaufman from Knopf Doubleday, an imprint of Random House, said in a widely reported statement that the book is "largely" set in Washington but "it's a Washington few will recognize."

The Lost Symbol will have a global English-language first print run of 6.5 million copies - the largest first print run ever by Random House, a unit of German media group Bertelsmann AG.

The Da Vinci Code has more than 81 million copies in print since its 2003 release and topped best-seller lists worldwide, outraging the Vatican and some Catholics because of the fictional story lines about conspiracy and the Catholic Church.

(China Daily/Agencies July 10, 2009)