Dan Brown's new novel, The Lost Symbol, the eagerly awaited follow-up to The Da Vinci Code, is to have a first print run of 6.5 million copies, the largest ever first print in the history of the publishers, Random House. The book is due out on 15 September. It will feature the same protagonist, Robert Langdon, from Brown's bestselling thriller, The Da Vinci Code, it was revealed yesterday. Brown has spent five years researching his latest novel in which the action takes place over a 12-hour period. Brown, pictured, said it had been a "strange and wonderful journey" to write the book. The Da Vinci Code's UK paperback edition, published in March 2004, spent more than two years in the Sunday Times Top 10 bestseller list. The novel has been translated into 51 languages. The bookstore, Waterstones, yesterday predicted that this sequel would be "2009's biggest book".