Tucked away on the Fox lot, inside a nondescript trailer labeled Stacked Productions — the placard from Pamela Anderson's 2005 sitcom was left hanging to foil interlopers — two dozen staffers slave over monitors containing America's most famous animated family in various high jinks, like Homer spotting a fallen treat: ''Ooooh! Floor popcorn!'' Signs of time crunch are everywhere. A chart of scenes with titles like ''Eski-Moe's Tavern'' is covered with colored stickers indicating completion status. A calendar is smothered in notes about production sessions and deadlines. And then there's the world's least gentle reminder: Above one poor soul's workstation, a digital clock counts down the time left until this motion picture of major proportions, The Simpsons Movie, must be surrendered to the studio authorities. ''We use it as a means to frighten ourselves,'' explains producer Richard Sakai, studying its unforgiving flashes: 16 days, 9 hours, 42 minutes, 6 seconds...5 seconds...4 seconds...

A doughnut's throw away, the film's writer-producers — James L. Brooks, Matt Groening, Al Jean, and Mike Scully — give notes on newly minted footage. ''If a joke's not working,'' deadpans Scully, ''put a loud car horn over it or a plane flying by.'' In one scene, three townsfolk come pleading to Mr. Burns. ''So you want some of my electricity, do you?'' snickers the sinister senior tycoon. ''Well, for once, the rich white man is in control!'' When the Springfield residents are chased away by ferocious hounds, the scribes look relieved. ''That's an area we've changed 300 times,'' says Jean, shaking his head. ''We should put in all the takes,'' cracks Groening. Retorts Jean: ''It'd be longer than Gone With the Wind.''

Indeed, this has already become one epic cinematic journey. ''It's very hard to believe the end of the road is here,'' muses Brooks. ''You're crazy not to be excited, and you're crazy not to, um, uh...'' He trails off before finding the right words with a grin: ''...wake up on a mattress full of flop sweat.''

No need for nerves, guys: You're only making one of the most anticipated films since the concept of ever was invented. On July 27, Fox's worshipped, Emmy-encrusted comedy — featuring Homer Simpson, a man so dumb he once called a spoon ''that... metal deelie...you use to...dig...food'' — finally hits theaters. The Simpsons Movie promises to be an emotional saga about a man who falls for a pig, ignores his wife's advice, and potentially dooms his town. It also aims to honor the show's rich history (coming this fall: season 19) with physical gags, corner-of-your-screen winks, and beloved Springfieldians (Nelson! Chief Wiggum! That old man with the ZZ Top beard!). Yet this 35mm mission wasn't easy: Cows were had, shorts eaten. But after all the blood, sweat, and Duff beers, Homer's helpers think they've created something entertaining enough to pay for, maybe even woo-hoo!-worthy. And they know what's at stake: a billion-plus-dollar franchise's good name. ''Nobody wants to be the one that rams the ship into the iceberg,'' says Groening, who first scribbled the Simpson clan in 1987 for Brooks' The Tracey Ullman Show.

Or as Jean sums up: ''As an event, I think it'll be somewhere between Sgt. Pepper's the album and Sgt. Pepper's the movie.''

There had been whispers, rumors, even discussions about a Simpsons movie for a long time. As in, let's brainstorm over Crystal Pepsi long. The closest flirtation came in 1992, when Brooks wondered if the first cut of the ''Kamp Krusty'' episode could be expanded into a feature. But back in those early, heady days of the show — when bootleggers hawked Bart T-shirts on street corners — the staff was too busy churning out episodes to multitask multiplex-style.

That wasn't the only hurdle. Fox had long balked at Brooks' terms, which were: Commission us to write a script, but if we don't like the results, we don't have to make a movie. ''It was a tough point for them to swallow,'' admits the producer. ''But it was very necessary for us to feel secure as we moved forward. It was an odd contract dispute — we were arguing against a green light.'' However, Tom Rothman wanted that green light badly, so when the current chairman and CEO of Fox Filmed Entertainment became studio president back in 1999, he persuaded the powers that be to accept Brooks' conditions. ''Regardless of what it said on a piece of paper, if Jim Brooks and Matt Groening weren't happy with the movie,'' reasons Rothman, ''it wasn't a movie we should make.''

While the big screen loomed as the ultimate challenge — ''It's like Mount Everest,'' says Jean. ''You try to do it because you can'' — most at Simpsons HQ thought they'd strap on the crampons after TV's longest-running comedy was retired. But as it became apparent that the series wasn't going anywhere, ''we figured we'd better get started,'' quips Scully.

In 2001, the main voice actors signed a three-season extension with a film provision. Brooks thought it'd be ''romantic'' to reunite with early-days Simpsons players, so he and Groening slowly assembled an all-star team. Veteran series director David Silverman was hired to helm. (He'd left Pixar in anticipation of the gig. ''Steve Jobs said if it'd been for any other reason, he would've been very upset with me,'' he recalls.) Longtime showrunner Scully and current showrunner Jean were tapped to produce. The latter must mainline Buzz Cola: Jean oversaw the writers' room while continuing episodic duties. The room was filled with ex-exec producers and scribes. (For you hardcores, that list included George Meyer, John Schwartzwelder, John Vitti, David Mirkin, and Mike Reiss; Ian Maxtone-Graham and Matt Selman joined in later.) Two high-profile yet not surprising exclusions: Sam Simon, who'd codeveloped the series with Groening and Brooks but left over creative differences in 1993; and writer-producer-turned-late-night-star Conan O'Brien, who Jean says would've ''laughed'' off an invite. ''That makes no sense,'' responds O'Brien. ''I cleared my talk-show schedule for a year at great financial cost to myself, got an apartment right outside the Fox lot, and told them I was ready to report to work. All I heard back was that they were having trouble finding me a parking space, and then they stopped returning my calls altogether. I am stunned and disappointed.''

When Springfield's finest gathered in 2003, they were well aware of the challenges — and skepticism — ahead. ''The idea of doing a movie spin-off from a TV show smells bad, y'know?'' says Groening. ''South Park was proof that you could do something really funny and different from the show. If you weren't familiar with South Park, it was a great movie, and if you knew it, then it was even better.'' There was also that weensy issue of digging up a fresh plot. Says Scully: ''Story-wise, character-wise, joke-wise...after 400 episodes, we feel like not only have we done it all, we've done it all three times, and the audience has been very kind not to notice.''

Soon, though, ideas began flowing like Squishees. What if the Simpsons discover that their lives are being filmed for a reality show? What if Marge leaves Homer after he cluelessly rents out their house for a porn shoot and she becomes a manatee rescuer? (This second pitch, from Jean, was later developed into season 17's opener, ''Bonfire of the Manatees.'') But it wasn't until Groening mentioned an article he'd read about a community battling hog-waste pollution that the writers found their hammy inspiration for the plot: Homer adopts a pig and dumps a silo of its leavings into an already iffy Lake Springfield; an environmental catastrophe is triggered, turning Homer into public enemy numero uno and putting the town in dire jeopardy.

Wait. The movie hinges on...pig poop? ''When you put it that way, which is the truth, it sounds a little crude,'' says Jean, ''but we've done it in the most sophisticated, elegant, satirical fashion possible.''

After each writer penned a 20-page portion of the script, they met at the Simpsons production offices to stitch together their beast — a pastiche of wild jokes — and begin reworking. Fortunately they had a mentor in the multi-Oscared writer/director/producer Mr. Brooks. ''You couldn't just slap four episodes together and call it a movie,'' says Scully. ''You need to let the audience into the emotion of the story. Sometimes when you are in a room full of guys, you're thinking of this really sweet Lisa line, but you just can't bring yourself to say it. And Jim is not afraid to find the heart.'' For a pivotal scene in which a crushed Marge bares her soul to Homer, Brooks would ask Julie Kavner for more than 100 takes. The result, according to Groening, ''is probably the most touching thing we've done in the history of the show.''

The screenwriters had to overcome more than mental obstacles, judging from the faint odor of Raid and musty uncle in the room. ''The carpet is covered with stains of sitcoms past,'' says Scully, ''and I think the Pauly Shore show was written in this room.'' Haunted by a cawing crow perched outside the door, they literally sweated out the script — the crappy AC unit was too loud to use — in this confined space, season after season. ''Most of the people in the room are used to running the show,'' says Groening. ''It could've been ugly, but it was really fun. Only a couple of times were there mock stranglings — you know, in the style of Homer strangling Bart. But that was never about content. It was about fatigue.''

Gradually, the movie's plot evolved. After Homer's toxic blunder, the Simpsons flee to Alaska, where Homer and Marge clash over whether to save Springfield. Meanwhile, Bart wonders if dorky saint Ned Flanders would be a better father than Homer, and Lisa falls for a green-activist Irish kid named Colin. In other news, Arnold Schwarzenegger is president, and the head of the EPA is evil.

In May 2005, 18 months after the writers' e-pig-phany, the voice actors — including Dan Castellaneta (Homer), Julie Kavner (Marge), Nancy Cartwright (Bart), Yeardley Smith (Lisa), Harry Shearer (Mr. Burns), and Hank Azaria (Wiggum) — received some surprising news. A script for a Simpsons movie had been written. ''I showed up, and the script — I couldn't believe it!'' exclaims Cartwright. ''It was thick. I'm spreading my fingers apart, trying to guess how much that is...'' Pause. ''That's, like, three inches!''

An animated field op is going down inside a pink building. Here at Burbank's Film Roman, 11 days before delivery, Silverman is putting out fires and lighting other ones, ninja-ing his way through phone calls and questions from staffers popping into his office: ''Thirteen feet, four frames? Great horny toad! It should've been 9 foot 4!'' ''Homer needs at least another in-between on this robot dance!'' ''Is this your recut based on his recut?'' During a break, he explains with a shrug: ''It always comes together at the end...but it's gonna be a nail-biter.''

Since January 2006, he's been fastidiously translating those yellow creatures to the big screen (with a different aspect ratio, for maximum wide-screen effect). ''I'm really glad it took us this long to make the film,'' he says. ''The computer technology [has improved] on every level, from compositing to editing voice. We could've never done this in '93.'' While nifty tech, an intricate color palette, a Hans Zimmer score, and a $65 million budget helped provide a more lush vibe for Springfield, Silverman remained true to the show's hand-drawn ethos. And his crews (at Film Roman and Rough Draft studios) often found new ways to fatigue fingers: A short angry-mob scene, teased in trailers, required up to 3,600 drawings.

Oh, handling the hundreds of pages of rewrites. That was a bitch too.

Simpsons episodes typically undergo heavy changes, yet this production endured endless additions, deletions, and punch-ups. ''I don't consider myself an environmentalist,'' says Scully, ''but even I felt bad about the number of trees that were felled during the writing of this movie.'' While you will see Green Day punk up the Simpsons theme song during their worst gig ever, Albert Brooks as EPA chief Russ Cargill, and a secret cameo (''the most trusted superstar in America sullies himself in our cartoon,'' hints Groening), contributions from Minnie Driver, Isla Fisher, and Erin Brockovich hit the cutting-room floor. Meanwhile, the regular cast remained on call. ''I felt like a fireman,'' says Castellaneta. ''We should've just lived above the recording studio and put a pole in.... I didn't know what stayed in, what went out. I couldn't even follow what the story was — I just knew it was funny.'' Recalls Cartwright: ''They'd say, 'Can you come in? We've got a little rewrite.' And I'm not kidding, it was down to one word.... I was amazed at how many different ways I could say that one word!''

Yet the most important word at Simpsons HQ was mum: A veil of secrecy was wrapped tightly around the project. In addition to your usual script-shredding and confidentiality-agreement signings, the ''Yellow Harvest'' alias — Sakai's wink to Return of the Jedi code name Blue Harvest — was used to confound the curious. And then, in March 2006, the producers cooked up a trailer that was slipped into theaters before Ice Age: The Meltdown. This surprise generated so much fan saliva, ''it just became fun to see how long we could keep it private,'' says Brooks. That included the leaking of bogus spoilers: Homer gets superpowers! Homer runs for president! ''We were always afraid we'd put out a false plot that might be better than the one we were doing,'' laughs Brooks.

Considering the stratospheric hopes of those line-reciting, episode-ranking fans, a little paranoia could be forgiven. Brooks, who says this project carries far greater expectations than any other in his career, confides: ''There are few things that make your blood curdle more than somebody saying 'I bet it's going to be the greatest ever!''' Adds Jean: ''I think if I felt any more pressure, I'd be a diamond.''

Thankfully no stones were thrown during a Portland, Ore., test screening in March. Audience response was positive, minus a few criticisms. As a result, the producers strengthened or lost secondary characters' bits — the film has 98 speaking parts — and ditched a meta end-credits gag in which resident aliens Kang and Kodos pick apart the film. Also from this rewrite came a trailer highlight: Homer playing with his pig while singing ''Spider-Pig/Spider-Pig/Does Whatever a Spider-Pig Does.'' After more screenings and tweaking — jokes were being added in the final few days — even the Sultan of Sweat was pleased. Says Brooks: ''I know the picture is funny.''

What the Simpsons masterminds also know is that trying to please all diehards and successfully corral 18 seasons of minutiae into 86 minutes and 45 seconds is like Homer trying to restrain himself in a candy store: Ain't gonna happen. ''Listen, I've stood in line for the restroom at Comic-Con every year, and whatever the big movie is, I've heard the real-life versions of Comic Book Guy, so we're prepared for all kinds of reactions,'' says Groening. ''Everybody's got a different idea of the perfect Simpsons experience. People are going to say, 'You put in Lenny — why not Carl?''' He pauses. ''We have both, by the way, for all those Carl fans out there.''

But have some of those Carl fans tuned out while holding their breath for the movie? Although the series still nets nice demos, it's not the juggernaut it was. During the inaugural 1989-90 season, The Simpsons averaged 27.2 million viewers; last season, 8.8 million. The show's principals would be concerned...if fans weren't persistently peppering them with movie questions. Fox's Rothman maintains that the wait signals that this isn't a cash grab. ''Look, it's a triumph it got done in the aughts,'' he says. ''We accepted a long time ago they were going to do this on their own time frame. We weren't worried because Homer Simpson was going to be a fantastic character in 2007 or 2010.''

Not that the producers are muttering Mmmmm...pan-demographic 200-mil grosser with unlimited sequel possibilities just yet. Warns Jean: ''We only have one penguin in our animated film.'' (But they do have a scene in this PG-13 affair that's already gained notoriety: Bart bares all during a skateboarding dare. Before you blanch at the prospect of seeing the little dude's little dude, Groening explains: ''It's a very simple oblong.'') Blockbuster or bust, the boys behind Bart wish to accomplish one sentimental goal: create a communal living-room experience. ''Whenever we show clips from an episode to an audience, it gets such an amazing reaction, [because] you're so used to watching TV alone,'' says Groening. ''I'm hoping a lot of people begin dating and marrying as a result of this movie — meeting in the lobby, sharing some popcorn, and taking it from there.''

Now that the union of landmark pop culture icon and silver screen has been consummated, where do the Simpsons d'oh next? ''At some big executive meeting, they said, 'What's the craziest Simpsons fantasy you'd love to see done?''' recounts Groening. ''I said, 'How about a giant blimp shaped like Homer that would fly over the Super Bowl?' And they go, '[pause] Any other ideas?' And I said, 'Okay, okay — 600-foot-tall statue of Homer. His head rotates once an hour. You eat dinner in his noggin, and at 10 p.m. every night, spotlights come out of his eyes and go around the city like the Bat Signal, then he tilts his head back at midnight and laughs, and it fills the entire city with laughter.' And they said, '[pause] Any other ideas?' And I said, 'No...that's all I got.''' Deliver the Best. Movie. Ever. and you guys can do anything you want to. Bonus points if it happens in under, say, 18 years.