BRADY PUNCH : SECOND MOVIE SPOOF OF '70S SITCOM TURNS EDGY, PACKS MORE OF A WALLOP.

Byline: Janet Weeks Daily News Staff Writer

A teen-age boy stares through a thin curtain at the outline of a girl undressing in an attic. In the background, a guitar wails out the sultry strains of the '70s hit ``If Loving You Is Wrong.''

The boy is dumbstruck. Awe-struck. Love-struck, in a big way. This is lust, bigger than the biggest platform shoe, wider than widest furry sideburn, brighter than the brightest happy face sticker.

Wa-a-ah wails the guitar. ``Am I wrong to hunger for the gentleness of your touch?'' coos singer Luther Ingram.

And ``Eeew'' goes the audience.

See, these kids aren't the beautifully bad bed-hoppers of ``Melrose Place.'' This is - aack! - stepbrother and stepsister Marcia and Greg Brady getting ready for night-night in ``A Very Brady Sequel,'' which opens today.

What? Marcia and Greg Brady, avatars of wholesomeness, acting, well, aroused? Greg and Marcia, following each other around the clan's earth-toned San Fernando Valley tract home like little magnets? A Marcia and Greg ooglefest?

Oh yeah. And that's not the only time ``A Very Brady Sequel'' pushes the edge - the edge of good taste and the edge of good Bradyness - in an effort to distinguish itself from last year's surprise hit, ``The Brady Bunch Movie.''

Like the first film, the sequel mines old episodes of the TV sitcom for goofy plot lines, including the show in which Marcia and Greg argue over who gets the attic.

But unlike the first film, which grossed about $60 million domestically, the new movie gives the old show a dark spin. Not Harvey Keitel dark, mind you. But dark enough to make the silly squabble over attic space really creepy, as a Brady would say.

``It's meaner and a little edgier than the first time around,'' says Gary Cole, who plays Mike Brady, the head of the clan and a pathological lecturer. ``Obviously, we pushed things further and put these characters in situations that they would never be in in the television show.''

The decision to give the movie a bit of bite helped bring the cast back, Cole says. The actors were leery about sequel, fearing the joke was over. After all, is there anything left to say about the Bradys, icons of '70s kitsch, clashing like bad Quiana shirts with the world of the '90s?

But in this film, the fish-out-of-water element that drove the original is downplayed. Instead, the plot twists around a strange little mystery: Carol Brady's first husband suddenly appears in the form of Tim Matheson, a shady adventurer out to recover a valuable stone horse from the Brady household.

(Fans of the TV show may recall that the fate of Carol's first husband was never quite made clear. Mike Brady was a widower. But because audiences in 1969 weren't ready for a divorcee on a family show, Carol's status was deliberately ambiguous.)

Matheson's con game takes the clan to Hawaii, where they lampoon a trio of ``Brady Bunch'' episodes filmed in Hawaii in the 1972-73 season.

The new film's mystery and edge make the sequel work, Cole says.

``Every time you go out and try to do a sequel, it's an iffy prospect,'' he says. ``There are a lot of traps. If all you do is try to top yourself or repeat the same movie that you did before, that's usually a mistake. You can't recapture something that works.

``But I thought they had another idea. It was a different kind of movie.''

The most dramatic difference is that the script gives the Bradys hormones, which is sort of an inside joke. In his book ``Growing Up Brady,'' Barry Williams, who played Greg on the original ABC sitcom, confessed that he and Maureen McCormick (Marcia) developed crushes on each other and often made out on the set.

Still, playing out an attraction between Marcia and Greg was strange, says Christine Taylor (the new Marcia), a bona fide Bradyphile who also portrayed the character in ``The Real Live Brady Bunch'' stage show.

``It really felt incestuous,'' says Taylor, who stars this fall in Fox television's new sitcom, ``Party Girl.''

``On the set the day we shot our kiss, there was just silence.''

``I had to walk off the set,'' confesses Jennifer Elise Cox, who plays the subtly insane middle sister Jan. ``I couldn't take it.''

Christopher Daniel Barnes, who plays the big-screen Greg, says he found the kissing part equally yucky.

``It was weird,'' he says. ``It was like kissing my sister.''

There are other inside jokes, too, including references to other ancient sitcoms (``I Dream of Jeannie'' and ``Gilligan's Island'') and references to the original Brady series.

For Matheson, who never watched the show before being cast in the movie, immersing himself in the polyester world of boys with perms and girls with hair of gold was ``really bizarre.''

``I was not into the Bradys when I was a kid,'' Matheson says. ``I was too hip. I was going the other direction, counterculture.''

To bring himself up to speed, Matheson watched Brady reruns on TV every morning before work.

``So I would go from watching an hour's worth of the Bradys to walking on stage. It was really bizarre, like an acid flashback.''

Speaking of acid flashbacks, the sequel also features a scene in which housekeeper Alice (Henriette Mantel) accidentally dumps magic mushrooms into spaghetti sauce. She and Matheson eat the psilocybin-laced pasta and spend a few hours tripping. The trip is animated in bright Peter Max style.

``We go right up to the edge and look into the Brady abyss of distasteful humor,'' Barnes says of the drug scene. But he says he's not worried about offending die-hard Brady fans.

``We already offended them with the first movie.''

Matheson, however, says concerns about audience reaction to the Bradys getting high - even inadvertently - caused the mushroom scene to be rewritten. Originally, the whole family eats the spaghetti.

``They felt, and rightly so, that it was inappropriate to deal with children taking drugs. They're walking a fine line to make something funny. You don't want to glamorize drugs, God knows.''

Indeed, ``A Very Brady Sequel'' is no ``Trainspotting.'' It's part of a well-known American franchise, and producers know better than to tamper too much with the Bradys' goofy wholesomeness. So the movie exaggerates the TV show, but more often simply mirrors it.

For example, Jan Brady's jealousy of her beautiful older sister is a running theme blown up beyond the TV show. But it was also part of the original show.

For actress Cox, playing the nutty Jan is fun, but she fears being typecast as a neurotic.

``I'm trying to get roles that are very different from Jan,'' she says. ``I said to my manager, `I don't want to get typecast,' and he said to me, `I don't think there will ever be another role like Jan Brady unless it's `Welcome to the Dollhouse.' ''

CAPTION(S):

3 Photos

Photo: (1--Cover--Color) Here's ANOTHER story of those p esky Bradys

(2) A house of cards gives architect Mike (Gary Cole), center, with Carol (Shelley Long), the opportunity to impart a few words of wisdom in ``A Very Brady Sequel.''

(3) The new feature film takes the Bradys back to one of their '70s haunts - Hawaii.