The third big-screen adaptation from author Dan Brown's investigational mystery series (following 2006's "The Da Vinci Code" and 2009's "Angels & Demons"), "Inferno" is concurrently more of the same and a whole lot less—diverting on occasion, preposterous in the extreme, and ultimately disposable. If nothing else, director Ron Howard (2015's "In the Heart of the Sea") keeps things moving; there is barely a moment for the characters to breathe as they run from one locale to the next. The clunky screenplay by David Koepp (2012's "Premium Rush") is less assured, full of goofily far-fetched developments and a preponderance of exposition as the people on screen explain what is going on to each other. Even after all this racing around while talking, the plot cannot hold up to scrutiny, close or otherwise.

Harvard University symbology professor Robert Langdon (Tom Hanks) wakes up in a hospital in Florence, Italy, with a gash on his head and no memory of what happened to him or how he ended up an ocean away from Boston. Before he can answer these questions, he and his doctor, Sienna Brooks (Felicity Jones), are on the run from shadowy assassins determined to retrieve a thumbprint-activated biotube Robert finds in his pocket. Called the Faraday Pointer, it holds Botticelli's painting of Dante's Inferno with hidden clues to the whereabouts of a cataclysmic virus powerful enough to bring about a worldwide plague.

Robert Langdon is a whiz at deciphering minuscule-in-size codes found on all varieties of artwork, and his abilities are all the more miraculous here as he nurses a brain injury that has caused him to forget the word "coffee." The twists, turns and double-crosses come fast and furious in "Inferno," a film that demands a total suspension of disbelief. Treated as a slick, patently absurd entertainment, it works about half the time, usually when the chit-chat takes a backseat to daring escapes and chases through picturesque historical settings. When a handful of key revelations make themselves known and the actors begin to prattle on about their weak motives and convoluted actions, the narrative grows more burdensome even as it reveals itself to substantively be about very little as a whole.

As Robert Langdon and Sienna Brooks, Tom Hanks (2016's "Sully") and Felicity Jones (2014's "The Theory of Everything") are watchable to a fault, adept and believable enough to make their relatively thin characters surprisingly involving. One is happy to follow them, which makes their separation in the second half especially disappointing. Having played the same role three times now, Hanks is left unchallenged. As penned, there is simply not much complexity to Robert outside of his keen intelligence. Ben Foster (2016's "The Finest Hours") makes an impression with fleeting screen time as Bertrand Zobrist (Ben Foster), a billionaire bioengineer with a radical plan to control the world's overpopulation. Perhaps the supporting cast member to leave the biggest imprint, though, is a relatively peripheral one: the instantly charming Ida Darvish (2007's "The Astronaut Farmer"), stealing her scenes with humor and grace as Palazzo Vecchio employee Marta Alvarez.

"Inferno" tells of a far-flung scheme so intricately designed one has to question if there might have been a simpler, quicker way to save the world. Meanwhile, the viral treasure hunt at the picture's center consists of clues that must have taken the terrorist masterminds years to methodically map out. Above all, the chase is the thing, and while "Inferno" has its moments—a set-piece taking place in the treacherous rafters of the Palazzo Vecchio is full of high-wire suspense—it is often clumsily written and dissipates in impact as it goes. The overuse of subpar CGI to depict everything from a serpent to rivers of blood to soothsayers with heads ripped backward additionally pulls the viewer out of the story. The first of the Dan Brown adaptations, "The Da Vinci Code," was provocative in a way few Hollywood thrillers are. The derivative "Inferno" has noticeably less on its mind.