You see the hat before the hero — that famous fedora, the one that stays put through every tricky situation, or at least at arm’s length for a hasty getaway. And of course he still has the whip, the paralyzing fear of snakes and the catchy John Williams theme song that will surely gnaw at your brain for hours afterward.

Yes, “Indiana Jones and the Kingdom of the Crystal Skull” dives headfirst into the iconography of the franchise, which will bring a smile to your face and warm you with nostalgia. It’s admittedly a pleasure to see Harrison Ford back in the role.

Once you get past the initial reintroduction, though, it’s obvious that this fourth film in the Indy series really has no idea where to go. Except for the opening — which literally starts the film off with a bang — and a couple of dazzling chase sequences, “Indiana Jones and the Kingdom of the Crystal Skull” is about as unfocused and meandering as the title itself.

It’s been 19 years since “Indiana Jones and the Last Crusade” (which, apparently, was the second-to-last crusade) and 27 years since Steven Spielberg introduced us to the intrepid, quick-with-a-quip archaeologist Dr. Henry “Indiana” Jones. He’s grizzled and lined and he knows it, and he knows we know it — at 65, Ford is old enough to pay the senior citizen price for a ticket to his own summer blockbuster — but he certainly seems up for the challenge. Or at least his stunt double does.

Instead of the breathless action of previous films, though, this one gets draggy and repetitive in the middle, with Indy and Co. traipsing through various tombs, searching by torchlight for clues to the origin of the mysterious and powerful Crystal Skull of Akator. (What the thing is, or what it does, doesn’t really matter. It is the MacGuffin, as they say. But it does look eerily like Larry King.)

The fear that fanboys have long held is justified: that technology unavailable during the first three Indy movies would make this one look slick and fake. That’s especially true during the protracted, messy climax. But even before that, everything feels so glossy and detached that there’s never reason to believe the peril is real — it all lacks the tactile feel of, say, a giant ball bearing down, a wobbly rope bridge groaning over a chasm or horseback chase through a dusty canyon.

Spielberg fashioned part one, “Raiders of the Lost Ark,” as a fun and funny, rough-and-tumble homage to action-adventure pictures of the 1930s and ’40s. It’s still a classic that holds up beautifully today, and is far and away the best of the franchise. “Crystal Skull” (someone’s gotta shorten that title) feels like an homage to Spielberg himself: sort of a prequel to “Close Encounters of the Third Kind,” with a dash of “Duel” and the daddy issues that have permeated most of his movies. (Spielberg directs from a script by David Koepp and a story by Jeff Nathanson and old friend George Lucas, who’s also an executive producer.)

There are other not-so-subtle film references, like when Shia LaBeouf enters on a motorcycle, decked out in leather and an off-kilter hat to look exactly like Marlon Brando in “The Wild One.” Cate Blanchett, meanwhile, plays a villainous Soviet agent with the thick accent of Natasha from the old “Rocky & Bullwinkle” cartoons.

Both allusions are time-appropriate, though. “Crystal Skull” begins in 1957 Nevada, with Indy and his partner Mac (Ray Winstone) trying to escape from the Soviets who’ve kidnapped them. Blanchett’s fearsome Irina Spalko wants them to locate the crystal skull within Area 51 for some kind of nefarious mind-control plan involving alien intelligence (a long-standing Spielberg subject).

A former colleague of Indy’s, Professor Oxley (John Hurt), also was after the skull — and went missing in pursuit of it. LaBeouf’s young tough Mutt Williams tracks Indy down and pleads with him to help find their mutual friend, which sends the two on a quest to determine the purpose behind the mystical artifact and keep it out of the wrong hands.

Mutt’s significance, though, will be immediately obvious to everyone but Indy, especially when Karen Allen shows up as sharp-tongued old flame Marion Ravenwood from “Raiders.” LaBeouf, a Spielberg favorite, does just fine opposite Ford in a physically demanding role and is clearly and deservedly being groomed for great things; meanwhile, seasoned actors like Blanchett, Hurt and Winstone go to waste in one-note parts.

But the film’s interpersonal relationships and revelations should matter — they should give the film heart and weight as they did with Sean Connery’s lovably goofy presence as Jones’ father in “Last Crusade.” Here, they feel like a given, a blip, a speed bump on the way to bigger and more spectacular set pieces involving waterfalls or machine-gun fire or giant ants in the Peruvian jungle.

And if there’s not much in the way of emotional investment, there’s even less humor. The cheekiness that made Indy so charming — the swagger and the sarcasm — are long since gone. Much of what made the character so compelling, beyond the adventures he took us on, was the fact that he seemed like an entertaining guy to hang out with, or at least one who would be consistently unpredictable.

Now, even his students don’t have schoolgirl crushes on him anymore. Maybe that means it’s time to hang up the fedora after all.

“Indiana Jones and the Kingdom of the Crystal Skull,” a Paramount Pictures release, is rated PG-13 for adventure violence and scary images. Running time: 126 minutes. Two stars out of four.