'Time, the subtle thief of youth." It's a line from the poet John Milton, but not the line that's cited by a crazy old professor in

Indiana Jones and the Kingdom of the Crystal Skull

. That bit o' Milton is about death - "the palace of eternity."

Nineteen years have passed since the wise-cracking, whip-snapping archaeologist adventurer Dr. Henry "Indiana" Jones last dashed around the globe - and cashed big bucks at the box office. Indy's gait was quicker then, his stance straighter, and his delivery. . . well, his delivery was about the same. Terse, cranky, unmusical.

But the passage of time is definitely a theme in this ballyhooed third sequel to 1981's Steven Spielberg-directed, George Lucas-produced Raiders of the Lost Ark. (OK, the first follow-up, Indiana Jones and the Temple of Doom, was technically a prequel, if you want to get picky.)

Set in 1957, at a time of Cold War dread (Commies, nukes), and starting in the American Southwest - before hopscotching to the Amazon and the jungles of Peru - The Kingdom of the Crystal Skull finds Harrison Ford reunited with his fedora and bomber jacket, muttering archaeological mumbo jumbo (check out those "geoglyphs") as he runs, jumps and socks his way through relentless chase sequences in search of, um, a mystical, ancient something-or-other.

That would be the Crystal Skull of Akator, a storied artifact whose powers, in the wrong hands, could be awesome. Enter the awesome Cate Blanchett, sporting a Louise Brooks wig, a jumpsuit from the house of Hammer & Sickle, and a Russian accent borrowed from Rocky & Bullwinkle's Natasha Fatale. The Oscar-winning thespian is Irina Spalko, a spy with paranormal prowess, and Indy susses her nationality in a rare show of wit: by noting how she sinks her teeth into her "wubble-ewes."

By the time the Crystal Skull is over, Blanchett has dogged Dr. Jones and company across hemispheres, down waterfalls and through armies of carnivorous ants, and has engaged in a swordfight with Shia LaBeouf - the two whacking each other from the flatbeds of two trucks hurtling side-by-side through dense, monkey-festooned rain forest.

LaBeouf, who makes his entrance on a Harley (striking a Marlon Brando Wild One pose), turns out to be the son of Raiders sweetie Marion Ravenwood (Karen Allen, in a sunny reprise). And, if the franchise drags on into subsequent decades, the young actor has clearly been designated the heir to Indy's bullwhip. But whether it's his American Graffiti pompadour or David Koepp's dopey dialogue, LaBeouf never quite shakes off a vibe of awkwardness. Like, What am I doing here with these guys?

The rest of the principal cast is of classy British stock: Ray Winstone as Indy's not-so-trusty partner, John Hurt as the aforementioned Milton-quoting loon, and Jim Broadbent as a collegial college don. And if there's any doubt that it's Spielberg at the helm, check out the sinister G-men (a motif since E.T), or check out, well, it'd be a huge SPOILER to note the other Spielbergian motif running through Crystal Skull - but by no means a huge surprise.

While the production values are top-notch, and the action artfully choreographed, in the end - and quite well before the end - a sense of tedium sets in.

Since Raiders, Temple of Doom (its cranked-up violence led to the MPAA's implementation of the PG-13 rating) and Indiana Jones and the Last Crusade, there has been lots of similarly neo-nostalgic, retro-action fare out of Hollywood. The Mummy movies (a third coming in a couple of months) and the National Treasures, too, have paid homage to the cliff-hanging action serials of the 1940s that inspired Messrs. Spielberg and Lucas in the first place.

Like Indy's trademark chapeau, there's something a little old about all this digging around in ancient vaults, cracking open hoary tombs, dodging big boulders and hundreds of bad guys.

Old hat, that is.