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Like most kids grew up in the 80s, I had plenty of exposure to the games, mazes, and puzzles on the back of cereal boxes. The more kid-friendly the cereal, the better the games and puzzles on the back of the box. Sadly for me, we were a Raisin Bran and Cheerios family. Since the people at Kellogg’s knew that cereal in shades of brown were mostly for adults, instead of helping Cap’n Crunch navigate passage through the Wild Berry Sea, we got summaries of research about whole grains and heart health along with the occasional half-assed fill in the blank word puzzles: “Rais_ns are f_n and hea_thy!!”

I thought of those puzzles while watching Inferno, the latest film in a series based on Dan Brown’s books about brilliant historian Robert Langdon. Inferno is a perfectly tolerable action mystery, but it feels like a half-assed puzzle compared to the sophistication of the previous stories. The series is known for its historical puzzles and layered historical sleuthing, but the central mystery in Inferno feels like such an afterthought that it’s kinda like we’re switching to Raisin Bran after a couple of Fruit Loops and Lucky Charms movies.

This time around, the mystery itself isn’t based in the past, but the clues are: Langdon’s going after a genocidal billionaire who left Dante-related hints about his devious plot in museums around Europe. Screenwriter David Koepp seems to know that this time around the riddles are not as compelling, so the added depth comes from the context in which Langdon is working to unravel the truth. Professor Langdon (Tom Hanks) wakes up in a Florence hospital with amnesia and horrifying visions, so questions about what’s real and who he can trust are even more relevant than usual this time around. Helpfully, he has he support of his ER doctor, Sienna (Felicity Jones). This is good news because Sienna is a genius. Apparently. Truth be told, no matter how many esoteric facts she spouts, it’s awfully hard for me to believe that a woman with an advanced IQ wouldn’t think to take her narrow 4-inch wedge shoes off when trying to keep her balance on a narrow beam 15 feet above the ground. But there are a bunch of newspaper clippings around her apartment describing her as a prodigy and she knows a lot about Dante, so whatever.

Anyway, the second half of the film is much better than the muddle first. While I’m confident that the confusion is director Ron Howard’s attempt to replicate Langdon’s uncertainty for viewers, it ends up just being frustrating. The second half, though, feels more grounded, which serves the film and the audience. In other good news, the second half also features more of Irrfan Khan. Khan is one of the highlights of the film in his role as Harry Simms, who is a…person who does some things in the course of his work running a private company. I can’t really say much more without spoiling anything, but take note: for my money the best scene in the movie centers around a discussion between Sims and Langdon in which Sims describes the “great deal of situational ebb and flow” in his work. You’ll agree when you get there.

Hanks is better in the second half of the film as well, in part because he’s doing more than just interacting with Jones’s Sienna. Jones is fine as the ingénue in Langdon’s life at the moment, though she’s not given much to do. Sidse Babett Knudsen (Westworld, Borgen) has a meatier role as a mysterious woman from Langdon’s past, and she’s much more interesting to watch.

Credit where it’s due, Inferno does get a couple of other things right. Probably most importantly, although the overarching mystery isn’t the most engaging or complex of the series, the reveal is satisfying when it comes. A more subtle point in the movie’s favor is the way the Howard handles violence. Increasingly, many people who talk about movies have expressed misgivings about PG-13 action films that lay bloodless waste to entire cities, or even planets, without a second thought. In Inferno, the major deaths are more gruesome than you’d usually see in a PG-13 movie, but the dead have faces and names. The decision to go with more blood but less death raises the stakes in a way that could be educational for the writers and directors of some of our recent superhero flicks.

It was always going to be hard for Dan Brown (and for Hollywood) to recapture the magic of The Da Vinci Code, and Inferno doesn’t do that. But Raisin Bran is never going to be Trix. Inferno is an adequate film in the same way that learning about raisins and cholesterol is an adequate way to pass the time while eating breakfast.