Starring Tina Fey and Amy Poehler. Rated 14A.

Agent One: “Hey, we just signed Tina Fey and Amy Poehler to a movie about sisters who visit their childhood home, only to find that their parents have sold it out from under them.” Agent Two: “Sounds great. Who’s doing the script?” Agent One: “Script?”

Of course, that package comes with the usual assortment of SNLers, a reliably pedestrian director (Pitch Perfect’s Jason Moore), and a very loose framework (here called a screenplay) credited to Paula Pell, a veteran SNL writer who also supplied material for the duo’s seemingly effortless Oscar hosting last year.

Here, the effort is more obvious, as a half-hour’s worth of business is stretched to quadruple that length, in order to give full range to the stars’ considerable ability to riff, sometimes raunchily, on the sketchy theme of one sister being an anal-retentive goody two-shoes and the other an irresponsible hellraiser. The film’s switcheroo finds Fey as the bad girl, while Poehler plays the romance-challenged neat freak. But these distinctions melt away once our gals discover that their Orlando, Florida, parents (James Brolin and Dianne Wiest) have dumped the family domicile. They decide to host a major reunion party for the kids they went to school with—most of whom haven’t left the area.

When old pals and frenemies show up, it becomes clear that the rest of the movie will depend on improv skills and the chemistry between colleagues like Maya Rudolph, Samantha Bee, John Leguizamo, and an especially annoying Bobby Moynihan. For sure, they come up with some funny bits—none of which the filmmakers were willing to jettison for the benefit of a sleeker running time. That still wouldn’t have made Sisters worth the talents of Tina Fey and Amy Poehler.