From Armageddon to the Bad Boys movies to Pearl Harbor and the 2007 Transformers, director Michael Bay certainly knows how to rouse a crowd. In Transformers: Revenge of the Fallen he does just that again in a movie that has been outfitted with all the components designed to make teenage boys drool — lots of noise, explosions, exhaustively fast-paced editing, amazing special effects, beautiful women as sex objects and even a whiff of drugs, albeit here employed playfully as a gag in which a middle-aged mother gets accidentally high.

It’s a pubescent dream world, but it’s also vibrantly entertaining, amusing, clever and sometimes surprising. After all, it does begin in 17,000 B.C. when cavemen are the first humans to encounter the giant robot Transformers. Actually, it would help in understanding the plot if one had at least nodding acquaintance with the story line which is based on a series of toys that look like robots and can be transformed into miniature vehicles with the flick of a wrist. The Decepticons (the bad robots) and the Autobots (the good robots) have come to Earth to wage their final battle and to search for a giant cube called “Allspark” which was the source of life and energy on their now-destroyed home planet. (One might have thought all this was settled in the first Transformers movie two years ago. Transfomers: Revenge of the Fallen has no particular reason for being other than the 2007 film was a huge hit and Hasbro, the Pawtucket-based toy company that produced it, wanted to keep its Transformers toy line in the kiddie public’s eye.)

A remaining shard of the Allspark has been kept in a secret, heavily guarded military compound. But what’s this? The film’s hapless hero Sam Witwicky has discovered another shard of the “Allspark” cube inside the old sweatshirt he wore saving Earth from the Decepticons in the first film. Shia LaBeouf, who secured his place in Hollywood with the first Transformers film, again plays the winningly low-key Sam who still has the 1976 yellow-and-black Chevy Camaro that can transform itself in seconds into a 20-foot-tall Autobot. The car, called Bumblebee (voice by Mark Ryan), follows Sam around like a faithful dog, weeping when Sam says he must leave it behind when he goes off to college in the East, later turning up on campus, having followed Sam to Philadelphia.

Wisely, most of the rest of the cast and crew of the original film are back as well, including co-writer Roberto Orci and actors Megan Fox as Sam’s girlfriend/sidekick Mikaela, first seen draped sexily over a motorcycle in a skimpy costume, Optimus Prime (voice by Peter Cullen), the head Autobot; Megatron (voice of Hugo Weaving) who crash-landed in the Arctic thousands of years ago; John Turturro as the self-important Agent Simmons, now hiding out as a deli counter man, but primed to prove his worth and save Earth from the Decepticons who want to blow out our sun. There also are robots who are disguised as ice cream trucks, truck cabs and that yellow Camaro.

The plot revolves around an attempt by the Decepticons to not only steal Sam’s shard of the Allspark cube to gain its powers, but also to probe Sam’s mind for the secrets of their world which have been stored there by the shard. Sam occasionally goes into a trance in which he begins madly writing down the strange alien symbols that appear to him.

Much of the action boils down to a protracted series of explosive encounters between the Autobots and the Decepticons staged from Shanghai to Paris to New York to the Egyptian pyramids at Giza to Sam’s own house, the giant robots body slamming each other for supremacy. In one exciting sequence, a Decepticon rips up a highway in Shanghai, sending vehicles flying and people fleeing. It looks very impressive, although the action shots have been edited so rapid fire that, as with the first film, sometimes it’s hard to tell whether it’s a Decepticon or an Autobot that’s winning.

The special effects truly are eye popping, however. At one point thousands of ball bearings hatch into scorpion-like robots. In another, the mystical shard turns household appliances into Decepticons that sound like the little monsters in Gremlins. Best of the litter is a tiny Decepticon who gets its eye shot out by Mikaela and eventually joins her and the Good Guys, becoming a rather endearing figure in the process.

For all the robot excitement, however, like the first film Transformers: Revenge of the Fallen is really held together by its human components. LaBeouf is perfect as the ordinary guy who is caught up in extraordinary situations, especially when he helplessly begins spitting out those strange symbols in his astronomy class while at the same time dismissing Einstein’s theory of relativity. In a strange subplot, although he loves Mikaela, Sam is tempted by the brazen Alice (Isabel Lucas), a nymphomaniac who flagrantly tries to seduce him, though we later learn her horrible secret.

For comic relief there’s Sam’s geeky, kitten-loving college roommate, Leo (Ramon Rodriguez), who can’t believe that he has been caught up in this otherworldly mayhem and is sometimes as much a liability as he is a plus; and Turturro’s Simmons, who comes on board for what he hopes will be the final battle. But don’t count on it. The film leaves room for a sequel and word is that Transformers 3 is already in the works. The Fallen may rise yet again, especially since the crew on this one hasn’t lost any of its momentum.

****Transformers: Revenge of the Fallen

Starring: Shia LaBeouf, Megan Fox, Isabel Lucas, Hugo Weaving, Josh Duhamel, John Turturro, Peter Cullein, Ramon Rodriguez, Julie White, Kevin Dunn.

Rated: PG-13, contains violence, profanity, drugs, dog sex.

mjanuson@projo.com