Dan Brown is shown May 3 in Rome after the premiere of the film version of Angels & Demons. The Masons get a benign portrayal in his new book, The Lost Symbol. (Andrew Medichini/Associated Press)

U.S. writer Dan Brown, who outraged the Vatican with his novel The Da Vinci Code, has centred his latest book, The Lost Symbol, around the Freemasons.

And modern Masons seem delighted, or at least resigned to the prospect.

Brown's novel, released Tuesday, again features Harvard symbologist Robert Langdon, the main character in The Da Vinci Code. This time, however, he's solving a mystery in Washington, D.C., involving a secret link between the Masons and the city's history.

The plot features an anti-Masonic video and an ancient Masonic pyramid containing a secret code.

"I have enormous respect for the Masons," Brown said. "In the most fundamental terms, with different cultures killing each other over whose version of God is correct, here is a worldwide organization that essentially says, 'We don't care what you call God, or what you think about God, only that you believe in a god and let's all stand together as brothers and look in the same direction."'

Freemasonry is an old fraternity dating back to the Middle Ages, and at various periods in history it has come under suspicion because its rules and rituals are secret. It requires belief in a higher power, but members may be of any religious background.

Joseph Crociata, who is a junior grand warden with the Masons of the District of Columbia, said he expects Brown will make the Masons seem more interesting than they actually are.

Some members are worried about their portrayal, but lodge member Darryl Carter said all he expects is some "artistic licence."

The Lost Symbol, by Dan Brown, is set in Washington, D.C. (Random House/Associated Press)

"We welcome Dan Brown doing his work, because Masonry has not had the kind of popularity that it once did and … a work by somebody of Dan Brown's calibre could really attract people to Masonry," Carter said.

In The Da Vinci Code, Brown angered many conservative Christians with a story line that involved Jesus being married to Mary Magdalene and having children whose bloodline survives to this day.

In Angels and Demons, he gave a negative portrayal of a religious cult similar to Opus Dei.

Masonry is not getting such a bad rap in The Lost Symbol, however, as Brown highlights its religious tolerance and portrays its rituals as benign.

The book centres around Washington landmarks such as the Library of Congress and the Washington Monument and refers to the Masonic gavel and trowel George Washington used in 1793 to lay the cornerstone of the U.S. Capitol.