THERE ARE unspoken yet semiconsciously understood little rules governing our attitude toward sequels. We don't just want to re-taste the flavor of the original movie. We want the whole experience all over again. So we set ourselves up for disappointment. To add insult to ticket-buying injury, we feel a little let down afterward, as if the moviemakers had reneged on the contract. We go for repetition, then fault the movie for repeating itself. It's a lose-lose proposition most of the time.

"Spider-Man 2" avoids this trap thanks to one inbuilt, dumb-luck reason: The original Marvel Comics story has some narrative developments. These events, which happen to Spider-Man, take more than one movie to occur.

I'm talking specifically about the relationship between Spider-Man (Tobey Maguire) and Mary Jane Watson (Kirsten Dunst). Usually, a superhero cannot find the happy medium between his secret life and the normal one he would love to live if only he hadn't been the victim of a gamma ray experiment or an interspecies evolution, or traumatized by the death of his parents, etc.

"Spider-Man 2" explores the possibilities of finding that balance between superheroic and normal life. I'll leave it at that. Plus this movie, directed with precision and an appreciation for (relatively) rich character texture by Sam Raimi, remembers all the fine elements of the original film (and the comic book story). It reprises them perfectly, including wonderfully choreographed, skyscraper-hanging fights.

And once again, you can expect that red-eyed, failure-prone vulnerability from Peter Parker/Spider-Man and his tortured relationship with Mary Jane. Oh, how exquisitely frustrating it is! In this installment (well, of course there are more films to come!), she is engaged to the good-looking, upstanding John Jameson (Daniel Gillies). There's no reason for her to look back at the scrawny Peter, who, for reasons only we understand, cannot become her lover. (A superhero doesn't need a romantic Achilles' heel, not with all those supervillains looking for weaknesses to exploit.)

But she does look back. She knows there's something there. And that frustrated passion is memorably underlined by Dunst's one-of-a-kind voluptuousness. As Mary Jane, she is pale, delicate, beautiful and built like Jessica Rabbit; and those green eyes convey her emotions with such emphasis, you're ready to push the conflicted Peter into her arms yourself.

Without this relationship, Spider-Man's just another superhero.

The movie also reprises the charmingly hokey affection between Peter and his Aunt May (Rosemary Harris). Seen through the prism of comic book sentimentality, it has a sort of old-fashioned poignancy. "Spider-Man 2" also brings back the movie's best caricature: tabloid publisher J. Jonah Jameson. J.K. Simmons, a fabulous character actor who was the memorable Garth Pancake in the Coen brothers' "The Ladykillers," is crackingly hilarious as Jameson, bent on selling papers on the defamed back of Spider-Man. Have Jameson and Rupert Murdoch ever been photographed together? It's worth investigating.

And in this movie, we have a fascinating villain: Otto Octavius (Alfred Molina), a scientist who (through the usual accident) is fused with the evil he has wrought, a man caught and forever connected to four metallic pincered arms. As this new creation, Doc Ock, he's powered by a lethal fusion of energy, enough to equal the sun (or something). Played with a combination of pantomime sensitivity and cackling evil by Molina, he's a reasonably compelling villain.

I say "reasonably" because Raimi and his cluster of writers (including Columbia native Michael Chabon and the great Alvin Sargent) could have taken this creation to higher heights. He's not as psychotically evil as you'd hope. And one huge opportunity is missed. The movie could have made a little more of Octavius's heartbreak over the love that he has lost, thanks to this evil transformation. (Again, I'll leave it at that.) Giving him fuller dimension would have raised "Spider-Man 2" to a higher level, making Doc Ock's Manichaean struggles (not only between himself and Spider-Man but within himself) formidable. But all in all, "Spider-Man 2" is as fine a repeat experience as our foolish, creativity-challenged tradition of sequelizing allows. You can't ask for more than that.

SPIDER-MAN 2 (PG-13, 120 minutes) -- Contains comic book violence. Area theaters.

Tobey Maguire's Peter Parker is back in uniform for the sequel "Spider-Man 2."