Hey, how did this happen? After driving the art and craft of moviemaking to some kind of new low in “Transformers: Revenge of the Fallen,” director Michael Bay went right back and made the third installment of the money-making, critically derided series. And he actually did it right this time.

It’s still more video game than movie, but (and I never thought I’d say this) “Transformers: Dark of the Moon” is honest-to-gosh kind of fun.

Oh sure, it’s dumb, and overbearing, and Bay still has a 12-year-old boy’s idea of what cool is. But Bay keeps the complicated mythology simple and clean, and you can actually see what’s happening in the action sequences. Given the track record, those are major accomplishments.

Hero Sam Witwicky (I really hope I can stop typing that name in movie reviews someday), played once again by Shia LaBeouf (I really hope I can stop typing etc.), is unemployed as “Dark of the Moon” opens, his duties as an alien-robot fighter officially secret.

He’s the hero of a Michael Bay film, so he does have a super-hot girlfriend (Rosie Huntington-Whiteley). And it comes as no surprise that he gets pulled back into yet another intergalactic war between Autobots (the good giant outer-space robots) and Decepticons (the bad).

The fate of the planet hangs in the balance, as ever. LaBeouf’s joined by previous cast members John Turturro and Josh Duhamel, as well as a new crew that includes homeland security chief Frances McDormand, corporate honcho John Malkovich (really just there to bring the weirdness in a few scenes), and “Hangover” scamp Ken Jeong. Patrick Dempsey provides the rich-guy rival for Sam’s girl.

The movie kicks in nicely with its long opening sequence, a batty alternate-history account of the Apollo program and what it was really doing up there on the moon. Some of Bay’s big-canvas images are irresistible: a Decepticon punching the Lincoln Memorial and sitting in the chair of our 16th president’s monument, or the madcap scene in which a skyscraper tilts over halfway as our heroes slide down the outside of it.

For a movie based on some Hasbro toys, “Dark of the Moon” has a loony grandeur; perhaps no other director could make a giant robot declare, “It is time for the slaves of Earth to recognize their masters,” and not burst out laughing. But Bay’s commitment to that kind of nonsense is strangely endearing.

Bay is so committed, he almost makes you forget that all of this noise, all this sheer effort, is devoted to a story about giant talking machines that change into cars. And then you remember, and then you desperately try to get in the mindset of a 12-year-old.

Instead of the incomprehensible manic cutting of the last movie, Bay actually stages the action scenes so you can see what’s going on, including some borderline-amazing long takes involving the Transformers charging down a D.C. freeway at 100 miles an hour and making stuff blow up. It’s almost as though Bay read his last reviews.

Technical prowess Bay has, no doubt. It’s only taste he lacks. But thanks to a clean through-line (and despite the 154-minute running time), “Dark Side of the Moon” gets it done. It’s the ideal merging of director and subject.

“Transformers: Dark of the Moon” (2½ stars)

Rated: PG-13 for violence.

Showing: Tuesday at Pacific Science Center and Thorton Place Imax theaters; Wednesday opening at Alderwood Mall, Everett Stadium, Monroe, Marsyville, Meridian, Metro, Woodinville and Cascade Mall.