It’s been thirteen years since the raunchy high-school comedy “American Pie,” about four pals vowing to lose their virginity before graduation, hit theatres, spawning a couple of inferior theatrical sequels (“American Pie 2” in 2001 and “American Wedding” in 2003) as well as a direct-to-video afterthought (“Band Camp”) and loads of imitators. Now comes “American Reunion,” an attempt at resuscitating a franchise that should have been left dormant. But obviously nostalgia—and greed—know no limit.

The problem with the picture is basically that it’s a lazy piece of work—so lazy, in fact, that it even declines to concoct an explanation for why it’s a thirteen-year reunion rather than the ordinary round-decade one, preferring a throwaway joke instead. Unfortunately that’s characteristic of a movie that expends little energy giving the characters any heart, content instead to offer a succession of cheesy sex gags, beginning with a masturbation double-header and concluding with a credit-roll blow-job bit, with plenty of other variations in between. Some scatological humor, of course, is added as well—along with a dollop of gay and ethnic jokes and the obligatory dose of sentimentality.

The set-up is pretty simple. At the urging of Kevin (Thomas Ian Nicholas), who wants to get away from his wife for a while, the buddies from the first picture decide to come home for their HS reunion. Jim (Jason Biggs) comes with wife Michelle (Alyson Hannigan) and their young son; he hopes to use the time to recharge their marriage. Unfortunately, he finds that next-door neighbor Kara (Ali Cobrin), whom he used to baby-sit, is now a stunning eighteen-year old with a crush on him and a nasty boyfriend (Chuck Hittinger). Oz (Chris Klein), now a famous TV sportscaster, comes with his stunning party-prone girlfriend (Katrina Bowden), but is inevitably reconnects with his old flame Heather (Mena Suvari), despite the fact that she has a rich, arrogant doctor for a boyfriend. And in his wife’s absence Kevin finds himself gravitating toward his erstwhile sweetheart Vicky (Tara Reid). Meanwhile Finch (Eddie Kaye Thomas) arrives claiming to be a world-traveling adventurer.

Missing from the group is the obnoxious Stifler (Seann William Scott), who wasn’t invited but shows up anyway and becomes the trouble-making leader of the pack. He serves as the sparkplug for much of the rowdier stuff here, though also as the unlikely catalyst for sappy friendship-centered stuff in the last reel, which winds up at the prom, no less. It’s there that all the couples are properly sorted out, including Finch with erstwhile band chubby turned bartender beauty Selena (Donna Ramirez) and Stifler with somebody else’s mom.

Other characters from the earlier films make appearances, too—folks like Sherman (Chris Owen) and the “MILF” guys (John Cho and Justin Isfeld). You might want to bring a scorecard to keep everyone in mind. But the one figure who stands out—and who’s just about the only reason to see the movie—is Eugene Levy as Jim’s dad Mr. Levenstein. He’s been widowed for three years—Molly Cheek is seen only in a photograph—and desperately lonely. Levy gets some good footage when he tags along with Jim and Michelle to Stifler’s party, and inevitably gets together with Stifler’s mom (Jennifer Coolidge). Seeing those two in the same frame is almost worth the price of admission in itself, but Levy has some other good moments too. He doesn’t save the picture, but he makes parts of it tolerable.

Of the rest, the ones who come off best, perhaps surprisingly, are Klein and Scott—the former because he’s simply likable, the latter because he’s unafraid to take his character as far as possible. Though that means that he’s asked by the scripters to do some pretty nasty stuff (like his encounter with a beer cooler, or another with a girl he remembers well), he also gets most of the good lines not handed to Levy. Biggs demonstrates why his star quickly fell, and Nicholas and Thomas remain the blandest of the troupe. The females, one must note, are all underused, with Hannigan looking rather more tired than one would expect—perhaps the duties of motherhood have worn too heavily on her.

“American Reunion” is well enough made, though the direction by Jon Hurwitz and Hayden Schlossberg doesn’t exhibit much verve, being content to let the action amble along listlessly to a running-time of nearly two hours. That gives us all the more time to see how synthetic the whole thing is. The result is a movie that proves you can go home again, but may encounter people you’d have preferred to forget.