Swooping down the canyon-deep avenues of New York City, blissfully indifferent to the wispy-thin strands that hold everything together, the Spider-Man franchise tackles its third installment like the first day of summer vacation - brilliant in its lack of ambition.

This summer has seen a roller derby of sequels (several sporting the number three in their titles) all bumping elbows trying to gain traction in the crowd. For many of them that means offering up exotic realities or equally flamboyant performances. We are treated to the dream-like mail call at Hogwarts or the Caribbean's first metro-sexual pirate. But for all their exertions, this season's blockbusters have met with uneven success - many of them too clever (or too cluttered) by half.

Sure "Spider-Man 3" has its share of costumes and gadgets. And, over the course of its running time, no less than three super-villains are trying do the spin-meister in, but the film's genius seems to flow from its determination to keep things simple and familiar.

For all the collateral damage of busted up skyscrapers and overturned cars, the essential story is that Peter Parker (Tobey Maguire) wants to get married and does a pretty inept job of going about it.

Not that things are entirely his fault. His friend, Harry (James Franco) still blames Peter for his father's death and to complicate matters he's gained access to dad's laboratory and the Green Goblin arsenal. Across town an escaped convict (Thomas Haden Church) stumbles into a physics experiment and emerges as an ambulatory sand sculpture. Finally, a sinister blob of space goo slithers out of a meteor and, having nothing better to do, attaches itself to the license plate of Peter's moped.

Poor Peter, every time he gets ready to pop the question Green Goblin Jr., The Sandman, or the sinister little space blob seem to have other plans.

Mary Jane is having career issues of her own and loses patience with Peter's superhero distractions. Pretty soon their relationship is on the rocks.

To complicate things a little bit, the space goo chooses the occasion to attack Peter and transform him into the Darth Vader of Spider-men.

OK, I know I promised simplicity and we seem to have a plot that is ping ponging in every direction. But the saving grace of "Spider-Man 3" is that it refuses to get caught up in its own machinations. For all the mutations and conflicts going on, the movie offers the barest minimum of explanations. Like a good summer vacation you're invited to just go with the flow.

"Spider-Man 3" invests its energy in the things it does best. The special-effects shots of Spider-Man swinging, clinging, or just plain falling off the towering landscape of Manhattan are artfully rendered. Director Sam Raimi has a special affection for fistfights and rescues performed on huge chunks of buildings slowly rotating in free-fall towards the street below. "Spider-Man 3" generates successive waves of vertigo that will clean out your adrenal glands by the time the movie is over (This is Raimi's third outing with the Spider-Man franchise and he's gotten very good at it).

When the action gets too dizzying - or just plain silly - the story returns to Peter and his moped. Tobey Maguire does fine work smoothing out any pretentiousness of the Spider-Man franchise with his goofy smile. His portrayal of Peter's dark side (under the influence of the space goo) is at times very funny.

"Spider-Man 3" is a summer movie with a summer ethos. It just wants to have a little fun and invites you to come along for the ride (bring your own moped).

Directed by Sam Raimi

Rated PG-13

(Three Stars)

Bruce Bulloch may be contacted via wseditor@robinsonnews.com