You'll have to forgive director Ron Howard and screenwriter Akiva Goldsman for being a little confused. The Oscar-winning team behind "A Beautiful Mind" seems to have mistaken Dan Brown's "The Da Vinci Code," a fast-paced, childishly written speculative thriller for The Greatest Story Ever Told. Clocking in at a soporific 149 minutes, the film adaptation treats "The Da Vinci Code" as gospel, rather than the airplane-read potboiler it was, which I guess means that some of the people who loved the book will love the movie. The failure to acknowledge that the book has a few warts leaves those flaws magnified on the big screen.

With several million copies floating around in hardcover and paperback, the plot of "The Da Vinci Code" is well known. When a curator of the Louvre is found murdered, Professor Robert Langdon (Tom Hanks) is called in. Is he there to unravel the curator's final messages or as a suspect? With the help of police cryptologist Sophie Neveau (Audrey Tautou) and eccentric scholar Leigh Teabing (Sir Ian McKellen), Langdon is soon fleeing the Paris police (led by Jean Reno's Bezu Fache) and several murderous religious types (including Paul Bettany as psychotic albino Silas). What the whole mess has to do with the Vatican, the Knights Templar, the Holy Grail and a deep dark secret involving Jesus will either strike viewers as profound or profoundly silly (Hans Zimmer's bombastic score pushes both reactions to the extreme), but despite some minor tweaking in the final act, there won't be any surprises for Brown's readers.

Goldsman has done nothing to change the dialogue from the book, which is a mistake -- as bad as Brown's words read on the page, they sound even worse coming from people's mouths. Goldsman also did nothing to tackle the film's structural problems, which is an even larger mistake. There are so many mini-lectures on so many subjects, that it's easy to forget that very little actually happens plot-wise in "The Da Vinci Code." There are one or two sticky situations as Robert and Sophie flee from various authorities, but even the story's vaunted puzzle-solving is a very minor element, with Langdon and his team really only cracking a few limited codes. In those scenes, Howard relies on the identical visual themes of floating thoughts and letters that he used to illustrate the mathematical process in "A Beautiful Mind."

Most of the screentime is, like the book, dedicated to condescending retellings of the past, with nearly every scene following an identical pattern: Character A notices a weird object and declares, "Surely that can't be the [Insert Bizarre-Sounding Relic Here]." Character B seems confused and replies, "What's [Bizarre-Sounding Relic]?" to which Character A says, "Well, I always thought it was a myth, but [Bizarre-Sounding Relic] is supposed to be..." Sometimes if there's a third character in the scene, Character A will yield the floor to another expert. Because Howard recognizes the limits of Brown's repetitiveness, he spices up the conversations with not-quite-evocative History Channel-style flashbacks and, in the case of Sir Leigh's 15-minute monologue explaining the entire movie, an effective little PowerPoint presentation on Da Vinci's "Last Supper."

It doesn't help that Robert Langdon is one of the most insufferable supposed heroes in recent literature or cinema. You wouldn't want to invite Langdon to a party, because he's the kind of know-it-all who can explain the source of every phrase, the truth behind every accepted historical myth and what wines go best with all meals and feels that with knowledge comes the mandate to convey his information even at inappropriate or irrelevant times. He's not a human character, but an amalgamation of pop-up trivia and pensive stares and there's nothing Hanks can do to make him sympathetic, interesting or engaging. The star, once among the mostly lively and reliable of comedic actors, manages to furrow his brow and look astounded for the entire duration of the film, a feat of endurance, but not acting. On the other hand, he wears a Mickey Mouse watch, so at least fans of the book will like the detail. Miscast though he may be, Hanks can't be blamed for writing that would have torpedoed any thespian.

Joining Hanks in the woefully wrong department is Audrey Tautou, whose gamine features and adorable phonetic English render Sophie little more than pert and pouty. As the evil albino, Bettany speaks in a varying accent and falls prey to Brown and Howard's dual obsessions with the character's bloody self-flagellation such that watching him is a chore. The film's only hints of wry wit are provided by McKellen.

Thanks to location shooting in Paris and London, Howard and cinematographer Salvatore Totino do an aesthetically appealing job of visualizing Brown's world and despite the predictable nattering from the Vatican and from Opus Dei, the film is very respectful of faith and only casts it aspersions on fictional sects within real-life sects. The big disappointment is that rather than taking an active role in the adaptation process, Howard and his team wasted a golden opportunity to make a movie that couldn't help but be better than the book.