Big, dumb fun, “Transformers” is an all-American blast of shock-and-awe action cinema. You do the blockbuster math: If you like car chases, then how about cars that morph into walking, talking robots from outer space primed for battle? What if it all happened on an Army base in the desert, or in running skirmishes between skyscrapers and under highway overpasses, or at the Hoover Dam?

Director Michael Bay recognizes the pressing question on the summer moviegoer’s mind: What if stuff exploded, and it was awesome?

Mr. Bay, best known for the glories of “Armageddon” and “Bad Boys 2,” knows the boisterous answers to these and other questions of wide-eyed, unself-conscious spectacle. “Transformers” is, for the most part, a slick, entertaining summer flick like the ones mom used to make — provided that your Mom was a 1990s action-movie director intent on realizing your playtime fantasies with 50-foot computer-generated death machines.

An origin myth kicks off “Transformers” — a “Superman” affair about the good (Autobot) and evil (Decepticon) exiles of a distant planet — but the real time and place for robot Creation lies closer to home: Hasbro, the early 1980s. The venerable company, adapting an original Japanese concept, unleashed a multimedia armada on the youth of America: the famous transforming two-for-one toys, a Saturday morning cartoon, a big-screen animated feature, video games, and a theme song with a demonically catchy refrain.

With eminent pop savvy, the new “Transformers” movie goes straight to the heart of the boys-with-toys appeal by introducing its teenage hero on the verge of getting his first car. Sam Witwicky, played by Shia LeBeouf with his likable Nickelodeon-safe blend of fast-talking antics and good-kid decency, convinces his dad to facilitate this American rite of passage. At the used-car lot, a yellow 1975 Chevy Camaro with racing stripes wins out, though it seems quite literally to have a mind of its own, communicating by radio songs and driving itself.

But while Sam is putting the curious car to use by angling for tanned-and-toned classmate Mikaela (Megan Fox), Earth is secretly under siege by evil robots. The first inkling of this Decepticon assault appears at a U.S. Army base in Qatar, during downtime for the troops. A jet-black helicopter of unknown provenance approaches, morphs monstrously, and proceeds to flatten, detonate, or hurl every soldier and vehicle within range. A set-piece played for maximal effect and decibel level, it’s a spectacular debut for the long awaited movie’s shapeshifters — bad guys always know how to make an entrance.

The noble Autobots appear soon enough, too, when the Camaro changes into noted Transformer Bumblebee, eager to save Sam’s skin from murderously inquisitive Decepticons. In classic adventure style, the overwhelmed teenager turns out to be central to the survival of the world. As the Autobots explain, repeatedly, he’s the last known link to the vital robot life force known as the “allspark,” by way of an ancestor’s funky discoveries in the Arctic.

The American military, led by Secretary of Defense Jon Voight, also races to figure out the Decepticon incursions with the aid of perky young hackers in cavernous control centers and a comically secretive division called Sector 7 (headed by John Turturro). One-off Transformer face-offs and rock ‘n’ roll-fueled chases build toward a glorious urban battle royale that makes the semi-coherent but exhilarating last 40 minutes more just “action” than “action movie.”

Buoyed by a surprisingly effective stream of wisecracks, “Transformers” gets the monster-truck idolatry of it all. The crashing, tumbling, striding robots are toys-turned-heroes, big friendly giants (or monsters), iron gods on earth. Visually, their metallic surfaces and bit-mapped workings draw you in. Instead of the clunkier models that populated the original “Transformers” feature in 1986, Mr. Bay’s machines uncannily resemble Boccioni’s dynamic 1913 Futurist sculpture, “Unique Forms of Continuity in the Space.” They also do what children do with the toys: bang together, narrate what they’re about to do, and make elaborate, long-winded “transforming” noises.

“Transformers” is electrified by Mr. Bay’s faith in action for its own sake, which turns into a kind of jingoism. Adapting a toy from the Reagan administration, he also seems to draw on an earlier, more comforting era of patriotism, indulging Autobot leader Optimus Prime’s hokey speechifying and illuminating his teens with “Morning in America” sunlight. The Decepticons could have been played for sleeper-cell stand-ins — zealots in disguise — but these anxieties are more apt to be defused, as with Mr. Turturro’s broad comic turn as a government agent with a “do whatever I want” badge. Sam’s rather ominous family motto is “No sacrifice, no victory,” but it helps to be backed up by Optimus Prime.

Liberal borrowing from other movies accounts for some other echoes of the past, from “Terminator 2” to “Superman,” to even lighter fare such as “Batteries Not Included.” (And where would the Camaro’s radio-playing antics be without the seminal innovations of Herbie the Lovebug?) But in a more modern sense, “Transformers” keys into the contradictory science-fiction appeals of technology as big, foreboding, foreign, and as small, intimate, and familiar. (One cackling, spider-monkey-sized Decepticon that hides as a radio or cell phone provides a perfect symbol for the double-edged age of the iPod.)

Mr. Bay may not be Steven Spielberg, but America’s real blockbuster auteur was an executive producer on the film, and I’m inclined to trust his bet in terms of mass appeal. “Transformers” is almost undoubtedly the first in a franchise, and it’s probably as good as the franchise is going to get, so it’s worth seeing Mr. Bay’s well-mobilized schlock now before someone makes the concept look like a video game in a bad way.