It’s safe to say that everyone and their mother loved bestselling author Dan Brown’s novel “The Da Vinci Code,” a genre-defining thriller that has sold a whopping 80 million copies since its original publication in 2003, along with inspiring a movie or two featuring Tom Hanks. 

What those readers might not know is that “The Da Vinci Code” was the second in a series of novels all tied together by the main character, a Harvard professor and world-renowned symbologist, Robert Langdon.

The sixth and latest installment, “The Secret of Secrets,” released on Sept. 9, puts Langdon and Katherine Solomon, a scientist studying consciousness from the third book, “The Lost Symbol,” and the first-ever returning love interest, to the test on a winding adventure.

In Prague for a ground-breaking lecture from Solomon about the nature of consciousness in anticipation of her polarizing manuscript, Langdon and Solomon find themselves thrust into a conspiracy they never asked for. The city of Prague itself — and several shadowy characters — has secrets to hide, secrets that could be exposed by Solomon’s mysterious manuscript. 

When Solomon goes missing, it’s up to a ragtag group composed of Langdon in Prague, Solomon’s publishing team at Penguin Random House in New York, and a U.S. ambassador to Czechia to get to the heart of why a shady London-based syndicate of the shadows would do anything to get their hands on an unpublished manuscript posing a new theory on the mechanics of awareness.

The Langdon series is popular for many reasons, though its most unique draw is the interdisciplinary balance Brown draws between science, fiction and action to not only contextualize a scene, but to drive an entire several-hundred-page novel on individual questions with multiple answers. 

In “The Secret of Secrets,” the question of consciousness can’t solely be answered by Langdon, with his background in art history and religious symbology — readers need perspectives from scientists like Solomon and politicians like embassy attache Michael Harris to make the novel’s conflict three-dimensional. Each point of view adds depth to the stakes as readers get to know characters new and old when they enter the pressure cooker that is solving Prague’s mystery.

Surprisingly, the character readers learn the most about in this novel is Robert Langdon. After five previous novels, it’s impressive that Brown has more angles of Langdon to explore rather than solely use him as a vehicle to feed fans another highly anticipated plot. That being said, while the romantic side of Langdon is fun to explore, his involvement in the mystery itself feels inconsequential at times.

Because the series is largely rooted in hidden messages within art and architecture, the novel’s focus on cognitive science relegates Langdon to a reactionary role within the novel, receiving explanations about Solomon’s discoveries here and there while using his knowledge of Prague and its history to escape ne’er-do-wells. Prague itself seems secondary to the greater plot of the mystery behind Solomon’s research, as if the book could have taken place in any city.  

Most of the information necessary to expand the scope of the narrative comes through memories, flashbacks and strictly stated exposition from scientists to the ignorant Langdon as opposed to the setting provoking the plot, a method that gets tiresome at times considering the novel’s 670-page length and the mystery being the content of a manuscript that Langdon hasn’t read.

The steady flow of exposition also highlights a series-wide issue: Dan Brown can’t write dialogue. He’s an incredibly talented weaver of plots and master of detail, but when it comes to dialogue in the Langdon series, it’s always a mode of information instead of elaboration. It helps that Langdon is a professor and his job is giving exposition about the world to ignorant students, but after the trillionth paragraph of summarized, heady science, it gets old.

But when reading a book of Brown’s, there are inevitable charms that keep readers from walking away, and “The Secret of Secrets” is no different.

The novel is Brown’s most creative yet, introducing a meta element that strengthens the overall argument of the book: Solomon’s editor at Penguin Random House and several members of the Penguin team are featured players in the novel and have characters named after them from Brown’s real-life publishing team. In a book about taking a look at one’s own consciousness, it’s a clever play on Brown’s part to do that himself in his own work. 

His writing is as engaging as ever, digestible and yet still stimulating for the average reader. Short chapters are littered with informative, dense paragraphs that are in turn punctuated with italicized thesis statements, keeping readers from getting lost in the steady flow of information. 

Rather than succumb to the world of theory and intellectualism — like the antagonists of the Langdon series often irresponsibly do with their scientific or technological studies — Brown has offered the world yet another thrilling and accessible peek into an interdisciplinary world often gatekept by academics.