When Dan Burstein read The Da Vinci Code in 2003, he was so excited by the book and the myriad historical ephemera it explored that he rushed to his local Barnes & Noble to find out what was true and what wasn't in Dan Brown's book. The search led Burstein on something of an intellectual wild goose chase—he wound up with more than 200 titles on subjects referenced in what became one of the bestselling books of all time.

Burstein, a journalist turned venture capitalist who wrote a number of books on technology and economics throughout the 1980s and '90s, turned his curiosity into his own bestseller, Secrets of the Code, which CDS (now Vanguard) published in 2004. That book went on to sell over 200,000 copies and launched the Secrets series, which now includes five books; all but one, on the TV show 24, deal with Brown works. As Brown's long-awaited new novel looms—Random House is publishing The Lost Symbol on September 15—Burstein is getting his team ready for Secrets of the Symbol: The Unauthorized Guide to the Da Vinci Code Sequel, which William Morrow just acquired from agent Danny Baror, for high six figures. The trick for Burstein is turning in a thoroughly researched book about a novel whose contents are being closely guarded.

Although Morrow won't publish Secrets of the Symbol until January 2010, that drop date, according to acquiring editor Peter Hubbard, still requires a quick turnaround—Burstein plans to deliver the manuscript six weeks after Brown's book is released.

The previous Secrets books, which relied on heavy input (through interviews and sometimes excerpts) from various experts in fields such as history, art, religion and mythology, have always been involved affairs—Burstein estimates that he used more than 50 writers and editors. He also goes to great lengths to get into Dan Brown's head. One of Burstein's team members is an investigative journalist who, among other things, tracks down people who have spoken to Brown. “We pick up codes and clues that he's actually left behind, and extrapolate and talk to people who know him,” Burstein said, declining to offer any names.

It's assumed that Brown's new novel will be set in Washington, D.C., and touch on the history of Freemasonry. Burstein knows this, in part, because his investigative reporter, David Shugarts, has been “intellectually following” Brown, for years. As a result of those efforts, Shugarts wound up writing one of the Secrets books, 2005's Secrets of the Widow's Son, which broke down potential subjects Brown might tackle in the book that was known as The Solomon Key. (Burstein said Sterling may reissue that book if Shugarts hits on much of what Brown actually explores in Symbol.)

At this point Burstein is flush with material; he estimated his team has organized information on over 100 categories and more than 1,000 historical figures, pieces of art and architecture. His team members have also spoken to “people in the hierarchy” of the Freemasons who've relayed questions that Brown directly asked them.

Despite the stalkerish behavior Burstein describes, he said he's really just a Dan Brown fan who, although he's got work to do, mostly wants to read the new book. “I look forward to being just as surprised as everyone else [when I read The Lost Symbol]. The only difference is that I bring to it six years, thousands of pages and hundreds of interviews that will inform my reading... and help me in my quest to write a meaningful book about what it covers.”

On the Trail of Dan Brown: Who Dan Burstein Thinks Might Appear in The Lost Symbol

—Albert Pike, a Confederate soldier and significant Freemason (Burstein said some think he's the “father” of the secret society in the U.S.).

—Vinnie Ream, the first female sculptor to be commissioned to do a work by the U.S. government—she did the statue of Lincoln in the Capitol rotunda—who had a 20-year platonic relationship with Pike.

—James Smithson, who endowed the Smithsonian Institution.