The third sequel in the excessively violent, R-rated “Die Hard” movie series, “Live Free or Die Hard,” is rated PG-13, which is an open invitation for parents to attend with their tween and teen broods. Here’s what they’ll learn about the PG-13 rating: So long as a film eschews sex, hard-core curse words, and cigarette smoking, filmmakers can weave a tapestry of brutal, wall-to-wall violence.

Dozens of innocents and bad guys are dispatched — bullet-ridden, charbroiled, or in pieces — to their graves. Will children older than 13 like it? Yes they will, and chances are you will too — that is, if exploring the classic narrative theme of Mack truck vs. fighter jet is your energy drink of choice.

“Live Free or Die Hard,” which opens today, is laughably exhilarating; you’ll applaud the comic book heroics and bone-crunching absurdity in equal measure. Compared to the current crop of blockbusters, which are the cinematic equivalent of Macy’s Thanksgiving Day Parade balloons, it’s a fantasy shoot ‘em up that defies physics with one combat boot planted on terra firma. Leave it to an aging, if still charismatic, action star who’s been known to cavort with young women a few years away from actually watching cartoons to deliver what a summer movie should be: a shot of adrenaline.

The original “Die Hard” remains the high-water mark for the action genre, the way “The Godfather” or “GoodFellas” transcend the base, pleasurable trappings of the gangster genre and approach something near art. In “Live Free or Die Hard,” director Len Wiseman has kept the hallmarks of the original in place: Bullet-resistant NYPD cop John McClane (Bruce Willis) is the right man at the right time, waging a oneman war against a brilliantly evil mastermind. Our hero engages in tense games of verbal cat and mouse over cell phones while the lives of beloved family members hang in the balance. Meanwhile, a colorful cast of supporting characters lends its support as Mr. Willis ping-pongs against walls and down elevator shafts, narrowly escaping balls of fire.

All the “Die Hard” flicks — the 1988 original, 1990’s “Die Hard 2: Die Harder,” and 1995’s “Die Hard With a Vengeance” — offer the same cynical plot: Supposed terrorists stage an act of dramatic anarchy in order to cover up their real intentions: the theft of a huge amount of money. It’s an apt pop-art reminder that for all the world’s militant extremist woes, the main motivator of terrorism isn’t religious ideology; it is, simply, greed. The plot in “Live Free or Die Hard” is suitably contemporary, and deals with a team of cyber-terrorists who hack into the government mainframe and start to systematically shut down the entire American grid.

Whether these techno-villains are anarchists bent on teaching America a lesson or just overachieving thieves doesn’t matter to McClane — take a shot at him or kidnap his daughter, and he lets slip the dogs of war. And those dogs have a mean bark: McClane launches a police squad car like a giant steel arrow at a helicopter, drives a truck through a wall into a butt-kicking villainess, and sends a wall-climbing bad guy into the jaws of some kind of giant turbine. As McClane, 52-year-old Bruce Willis writes a new chapter in the book for balding Hollywood action stars on how to maintain a credible box office allure. Mr. Willis is all smirk, bald head, and muscle, embracing the idea that his McClane is a laid back, over-the-hill superman. As a hacker under the protection of McClane, super nerd Justin Long carries the charms and flaws of Generation Y on his shoulders, as if his character was focus-grouped to death. But Mr. Long succeeds in letting his humanity shine a little, and contributes to the derring-do without becoming a comic relief or second banana caricature. As McClane’s daughter, Mary Elizabeth Winstead is allowed a spark of her father’s snarky attitude, and former “Deadwood” star Timothy Olyphant turns in an icy, borderline campy performance as Thomas Gabriel, evil computer genius and snappy dresser. Kevin Smith has a cameo as a computer geek living in his mother’s basement, and performs his duties with aplomb.

I’ll say one thing about Hollywood: The computers used in these types of movies run an operating system that looks like it was designed 10 years in the future. Crisp graphics fly across screens, immense downloads happen in a snap, and all you have to do is plug a doohickey into a thingamajig from a laptop that just survived an explosion, and you can instantly access any top-secret mainframe. Characters frantically typing at computer keyboards never looked so good, which is good because there’s a lot of it in between the steel, fire, and knuckles.

As I left the screening, I was privy to a conversation in an elevator between some critics slightly older than myself. They were dismissively complaining about how “Live Free or Die Hard” is one big video game. That it’s a video game is partly true, and the camera is fluid, snaking around the action without cumbersome quick edits, allowing the eye to drink in the insanity. When a movie with a video game aesthetic is done well, it can be breathtaking. And for good or ill, it is done very well here.

The message in “Live Free or Die Hard,” if there is one, is that wired, exercise-averse Generation Y needs no-nonsense, pain-don’thurt baby boomers to save them from the world. The irony, of course, is that it’s these same 20-somethings who are off fighting these terrorists around the globe, saving baby boomers from the world.