So I happily curled up with Robert Langdon, the author’s anodyne, tweedy doppelgänger, and suppressed my annoyance that the Harvard symbologist was still wearing his Mickey Mouse watch, hand-grinding his Sumatra coffee beans and refusing to entangle with the latest brainy babe who materializes to help untangle ancient secrets.

Image Credit... Illustration by Christoph Niemann

This book’s looker, Katherine Solomon, is a lithe, gray-eyed expert in Noetic science, the study of “the untapped potential of the human mind.” Brown must also want to explore the untapped potential of the human body, since he has made his heroine 50 years old, something that no doubt caused the Hollywood studio suits to spritz their Zico coconut water. Katherine, a few years older than Langdon, may be a tribute to Brown’s wife and amanuensis, Blythe, who is 12 years older and helped him write “187 Men to Avoid: A Survival Guide for the Romantically Frustrated Woman.”

Emotions are the one thing Dan Brown can’t seem to decipher. His sex scenes are encrypted. Even though Katherine seems like Langdon’s soul mate — she even knows how to weigh souls — their most torrid sex scenes consist of Robert winking at her or flashing her a lopsided grin.

Brown’s novels are obviously inspired by Indiana Jones and “Raiders of the Lost Ark.” But he can only emulate the galloping narrative drive and the fascination with mythological archetypes, pyramids, Holy Grails, treasure maps and secret codes; he can’t summon the sexy, playful side of the Spielberg-Lucas legacy.

His metaphors and similes thud onto the page. ­Inoue Sato, an intelligence official investigating a disembodied hand bearing a Masonic ring and iconic tattoos that shows up in the Capitol Rotunda, “cruised the deep waters of the C.I.A. like a leviathan who surfaced only to devour its prey.” Insights don’t simply come to characters: “Then, like an oncoming truck, it hit her,” or “The revelation crashed over Langdon like a wave.” And just when our hero thinks it’s safe to go back in the water, another bad metaphor washes over him: “His head ached now, a roiling torrent of inter­connected thoughts.”

You can practically hear the eerie organ music playing whenever Mal’akh, the clichéd villain whose eyes shine “with feral ferocity,” appears. He goes from sounding like a parody of a Bond bad guy (“You are a very small cog in a vast machine,” he tells Langdon) to a parody of Woody Allen (“The body craves what the body craves,” he thinks).

But Brown tops himself with these descriptions: “Wearing only a silken loincloth wrapped around his buttocks and neutered sex organ, Mal’akh began his preparations,” and “Hanging beneath the archway, his massive sex organ bore the tattooed symbols of his destiny. In another life, this heavy shaft of flesh had been his source of carnal pleasure. But no longer.”