By Dan Brown (Doubleday, $29.95)

Robert Langdon is back. The hero of Dan Brown’s super-mega-selling novels “Angels&Demons” and “The Da Vinci Code” has once again been called from his Harvard University classroom to solve complex puzzles, rescue a brainy, beautiful maiden and save the world from the forces of darkness.

Instead of Rome or Paris, “The Lost Symbol” finds Langdon in Washington, D.C. He has been lured to the Capitol rotunda by a mysterious religious fanatic, Mal’akh, who has kidnapped his mentor, Peter Solomon, the head of the Smithsonian Institution and a prominent Freemason.

Mal’akh wants Langdon to help him find the Masons’ Ancient Mysteries, “the lost wisdom of all the ages,” hidden somewhere in Washington. Like the albino Silas, villain of “The Da Vinci Code,” Mal’akh spent time in jail and remade his life through physical mortification — he castrated himself and is heavily tattooed — but it’s transcendence he’s after.

Solomon’s severed hand shows up in the rotunda soon after Langdon’s arrival, pointing at the dome. Can Langdon follow the signs? Soon the CIA is involved, saying Solomon’s kidnapping is a matter of national security. Langdon can’t tell whose side the Feds are on, so he takes off, helped by another Mason who works at the Capitol.

He travels through hidden tunnels, escapes the Library of Congress by impersonating a book, and teams up with Solomon’s younger sister, Katherine, a researcher who’s trying to find “the missing link between modern science and ancient mysticism.”

I wish I could report that Brown outdoes himself, but it’s hard to compete with two books in which your hero saves the Vatican from an anti-matter explosion and discovers that Jesus Christ has secret descendants living in France.

Freemasonry doesn’t have the dense web of associations that Catholicism has for many people — and Washington lacks the visual splendor of those ancient European cities, which Brown described so vividly in his last two books. That makes it harder to care when he spends pages lecturing you on ephemera. For me, the ending couldn’t come too soon.

Laurie Muchnick, Bloomberg