Splash, Too was made for television without the involvement of the original film's stars or director. The historical Apollo 13 didn't exactly lend itself to a follow-up. But Tom Hanks and Ron Howard were finally able to reunite for a sequel when they made Angels & Demons three years after The Da Vinci Code. Seven years later, Hanks and Howard are together again on Inferno, an adaptation of the fourth novel in Dan Brown's series of bestselling novels.

Few would argue that Hanks and Howards' first two Langdon movies inspired anywhere near the passion that Brown's books did. But the first grossed $759 million worldwide and the second earned another $486 M. Neither Hanks nor Howard has recently experienced such massive commercial success outside the franchise. So, here we go again.

After a short prologue, this threequel opens with Langdon (Hanks) in a hospital bed in Florence. He has a head wound and is rather disoriented. He is seeing disturbing visions of an Apocalypse, which is a bit like something the doomsday prophet Bertrand Zobrist (Ben Foster) of the prologue discussed before jumping off a tower to his death while being pursued by men. Langdon is treated by Sienna Brooks (Oscar nominee Felicity Jones, soon to be best known for Rogue One: A Star Wars Story), a Brit in Italy who rushes him to safety when a "police officer" approaches firing shots.

Langdon can't remember what has transcended over the past 48 hours, but Sienna is by his side to assume the leading lady duties held by Audrey Tautou in the first movie. She is a literate enough sidekick to tag along when puzzle-solver Langdon decides to go look for the death mask of the Italian poet Dante, who has history with Florence, a city from which he was exiled. Naturally, Dante's death mask, which has recently been stolen by Langdon (though he doesn't remember doing it), has some instructions written on the back to steer this mystery along. (The other big mystery -- the suspicious disappearance of Langdon's signature hairdo -- goes disappointingly unsolved.)

Langdon is pursued by multiple parties, including Christoph Bouchard (The Intouchables' Omar Sy), a Frenchman who claims he's with the World Health Organization. There is also Elizabeth Sinskey (Sidse Babett Knudsen), a mysterious woman with whom Langdon apparently has a past. Then there is Harry Sims (Irrfan Khan), a colleague of the deceased prophet. Khan steals his every scene as unexpected comic relief.

As usual in these kinds of movies, the world is in jeopardy. Apparently before dying, that fanatical prophet set about a plan to reverse some of the planet's rapid population growth by wiping out half of mankind with a deadly virus. It's up to Langdon and those he can trust to stop it and he fears he may have already been the first one infected.

David Koepp (Jurassic Park, Spider-Man) fully takes over the screenwriting duties that he shared on the previous movie with Howard's Oscar-winning A Beautiful Mind scribe Akiva Goldsman (who alone scripted Da Vinci Code). Koepp has a stronger body of work than Goldsman, but he can only be as good as Dan Brown's source text allows. And that isn't terribly good. On film at least, this series has never been one to command respect. Inferno is perhaps less disappointing than the original Da Vinci Code but also less engrossing than Angels & Demons.

This is a mediocre thriller, one that is beneath the talented international cast assembled and also Howard, even though his talents as a director have often been overstated. You can't blame Hanks for collecting an easy paycheck while getting to visit Italy and Eastern Europe. He's already turned in two of the year's best performances in Sully and A Hologram for the King. Nor can you deny the likes of Jones, Sy, and Khan the satisfaction of making a movie that many around the world will see. Even though they've all done that already or, in Jones' case, will do so soon, they haven't gotten to work with Hanks before.

Inferno is relatively easy to invest in, whether you're seeing it in "IMAX" as I did at my screening or on a regular-sized screen. Its climax, set in Istanbul's Basilica Cistern, is even moderately suspenseful. But this is never a film, always a movie and not such a good one at that.

Nonetheless, an audience is guaranteed to show up. Opening last week in some foreign territories, Inferno already grossed $94 million overseas. Although you can expect domestic returns to be down from the previous two, you can still be sure that the $75 million production budget will be recovered. And then what? Another film? Another hiatus is more likely. But when you think about it, is there anything to this franchise to make you really care where it goes next?