Where’s the fire?

“THE SIMPSONS MOVIE” begins, aptly, with a few scenes from the Itchy and Scratchy movie, a bombastic summer blockbuster based on the ultra-violent cartoon that Bart and Lisa love. At the climax of the movie within the movie, just as Itchy is pumping Scratchy full of nuclear missiles, Homer stands up in the theater and wails, “I can’t believe we’re paying for something we could get for free on TV. If you ask me, everyone in this theater is a big sucker, especially you.”

The issue of getting your money’s worth seems to have been high on the minds of the show’s writers, and with some reason. After 18 years on the air, the creators of the most trenchant, deceptively easy-to-swallow satire in the history of TV wanted to find a topic capacious enough to warrant bumping up the aspect ratio to widescreen. What they’ve come up with is an end-of-the-world scenario brought on by the town’s own carelessness. As Itchy and Scratchy bring the world to the brink of nuclear annihilation, the town of Springfield is nudged to the edge of environmental disaster by its own dumb hand.

In some ways, “The Simpsons Movie” feels a little like the Simpsons movie Lisa might have written. But it’s a strange path for the series’ star writers to have chosen -- this idea that more existential meant better. Of course, the jokes are pin-sharp and off-the-wall loopy as ever, and many sequences -- such as the one when Homer brings home his beloved new pet pig, and the one in which Flanders makes Bart a cocoa with about 15 special touches -- are inspired. But once the movie wanders into its contemplation of mortality and meaning, the trenchancy kind of creaks and falls off.

The movie opens with Green Day performing a benefit concert for Lake Springfield, the most polluted lake in the country. After concluding its set, the band ventures a few words on the dangers of living near a toxic lake, which naturally, nobody wants to hear. Eventually, the message comes directly from God -- via Grampa speaking in tongues -- a warning to the people of Springfield about a coming disaster involving “a twisted tail, a thousand eyes” and something called “eepah.”

If you’ve seen the Korean toxic monster movie “The Host,” you can more or less guess what happens next. Soon Springfield comes to find itself sealed off from the world inside a giant glass dome. When the townspeople find out who was responsible for the straw that broke the camel’s back (let’s just say Homer is involved), they come after the Simpsons with a vengeance. Like any good apocalypse story, “The Simpsons Movie” is full of strange reversals and portentous signs. You really know it’s the end of the world as we know it when Bart begins to wonder if he wouldn’t be better off as Flanders’ son and when Marge’s unfailing loyalty starts to fail. But the most unexpected thing about “The Simpsons Movie” is that although it expands its view to include panoramic Alaskan vistas and a more panoptic view of Springfield than we’ve seen, it doesn’t push the boundaries of the TV show in a narrative sense.

Unlike “South Park: Bigger, Longer, Uncut,” “The Simpsons Movie” doesn’t venture anything more transgressive than it usually does; it doesn’t take the gloves off. Sure, there are jokes equating the U.S. government with the only evil madmen capable of encasing a town in a giant cheese dome, but it’s nothing it hasn’t done before, and nothing we don’t hear every night on “The Daily Show With Jon Stewart.”

If anything, the movie feels a little safer (though I should say I stopped watching regularly years ago) than the show, focusing on the individual crisis and subsequent spiritual growth of each individual Simpson (with the exception of Lisa, who apparently didn’t need it).

In some ways, it reminded me of the final “Seinfeld” episode. As much as I laughed throughout, I kept wondering what was with all the emotional lessons. Strangest of all was Homer’s retreat to the cave (or igloo, in this case), where he experiences an epiphany and sees himself clearly for the very first time. In fact, “The Simpsons Movie” is basically a conversion narrative, in which Homer’s eyes are finally opened to the error of his ways. The turnaround feels like the end of something -- like, say, the series. Because where do you go from an (albeit briefly) enlightened Homer and sensitive Bart? The only place I can think of is off into the sunset.

carina.chocano@latimes.com

MPAA rating: PG-13 irreverent humor throughout. Running time: 1 hour, 26 minutes. In wide release.