If "Transformers: Dark of the Moon" isn't the summer's lousiest whiz-bang movie, it's only because there's so much competition. It's not even the best "3D anthropomorphic automobiles and explosions" movie of the month. The demolition derby of "Cars 2" seems a work of staggering genius in comparison.

Like "X-Men: First Class," this spectacle recasts a central showdown of the Cold War as a chapter in science-fiction lore.

In this telling, the noble Autobots and evil Decepticons with fiendish glowing eyes battled for control of their home planet. When the tide turned against the good guys, they retreated to Earth, while an ark containing the key to their world's recovery crash-landed on the moon in 1961. The Space Race was actually a competition between America and Russia to salvage the downed spacecraft's technology. Oh, and Chernobyl? Same story, later chapter. These days, the Autobots have become a freewheeling branch of the U.S. armed forces, zooming off to such locations as "Middle East: Illegal Nuclear Site" to lay the smackdown on swarthy upstarts.

We pick up our story with the Autobots' human ally Sam Witwicky (Shia LaBeouf) three months out of college and still unemployed, to his parents' chagrin. True, he helped save the world twice, but in today's job market it's all, "What have you done for me lately?"

His big break comes from a bug-eyed, grinning tycoon (that master of oddballs, John Malkovich) who challenges Sam to "impress me." It's hard to say exactly why Malkovich's turn is funny. Same goes for Ken Jeong's cameo as a hypertense executive who's on to the big space-cars plot, or John Turturro's return as a secret agent turned millionaire exposé author. They're not joke-funny so much as energetically off-kilter, winking at the postmodern irony of appearing in a movie about shape-shifting humanoid robots.

Michael Bay (the computer program created by producer Steven Spielberg to execute smash-bang summer blockbuster scripts) simply throws every possible emotional tone at the screen to see what sticks. If audiences laugh, it's a moment of comedy; if they shriek, it's horror. Frances McDormand barrels her way through several scenes as the rather masculine National Intelligence Director, managing to create something like an entertaining character and preserving her dignity in the process.

The other female character of note is Sam's girlfriend, Carly (Victoria's Secret mannequin Rosie Huntington-Whiteley), who makes her entrance as a pair of spectacular legs and a world-class rump mincing up the stairs to their bedroom. In Bay's worldview, women are either lissome damsels to be ogled, endangered and harassed, or fearsome emasculating shrews. Huntington-Whiteley, who has the emotional range of a voice-chip Barbie, is less affecting in her scenes with LaBeouf than is his tenderhearted Autobot bodyguard Bumblebee.

"Transformers" runs a soul-shredding 154 minutes, most of it a hash of time-killing subplots involving Russian gangsters, Patrick Dempsey as Carly's predatory boss and Sam's tour of duty in the corporate mailroom. The last 50 minutes are spent leveling Chicago, as the 'Bots and U.S. armed forces throw down, with Sam, Carly, Lt. Col. Lennox (Josh Duhamel) and retired Master Sgt. Epps (Tyrese Gibson) leading the counterattack.

Leonard Nimoy voices a new robot character named Sentinel Prime, who plays a key role in the hostilities, and allows Nimoy to recycle his "the needs of the many" line from "Star Trek 2: The Wrath of Khan."

There is exactly one novel idea among the slapdash battle scenes, as our human heroes slip and slide through a toppling skyscraper whose foundations are being devoured by a mechanical hydra. That flash of invention aside, the nonstop annihilation becomes obnoxious. The constant pounding does drive up one's bloodlust to lynch-mob levels, encouraging us to revel in the sight of evil Bots being ripped limb from limb. Take heed, would-be evildoers.

Roland Emmerich, who destroyed Washington in "Independence Day," New York in the 1988 "Godzilla" and Los Angeles in "2012," staged his cataclysms with visual-spatial logic and jagged jolts of wit. Bay's approach is to make the robots bigger, the explosions explodier and crank up the soundtrack until your skull goes numb. The appropriate response is a deafening yawn.