“Drinking Buddies” plays Thursday, Oct. 3 at 7 p.m. and Saturday, OCt. 5 at 9:30 p.m. at the Marquee Theater in Union South, 1208 W. Dayton St. R, 1:30, three and a half stars out of four. FREE!

While I admire the UW-CInematheque for its mission to bring unusual and challenging films to the big screen, I fear it may have gone too far with “Drinking Buddies.” A romantic comedy set in the world of craft brewing? Who’s going to want to see that in Madison?

The truth is, of course, lots of people, especially since Joe Swanberg’s film is so good, simultaneously grounded in real emotional behavior and effervescent in its comedy. And it doesn’t hurt that the Cinematheque is screening it at the Marquee, where you can bring in a great craft beer purchased downstairs at the Sett.

Kate (Olivia Wilde) and Luke (Jake Johnson) are best friends working at a Chicago microbrewery — she’s an event planner in the front office, he’s one of the bearded, trucker-cap wearing brewers in the back. They have one of those platonic relationships that’s casual but deep, going from teasing insults to back rubs and back again. And, after hours, both can hold their own at the bar when their comrades falter. It’s almost like a brother-sister relationship — except there’s something more, buried deep, that neither chooses to acknowledge.

Both are involved with other people. Luke is living with Jill (Anna Kendrick), and they’re talking about marriage, or at least talking about talking about marriage. Kate has been dating Chris (Ron Livingston) for a few months, and that seems like less of a good fit — he buys her a John Updike book as a present, for heaven’s sake.

All of this couples tension comes to a head when the foursome goes to Chris’ parents’ lake house for the weekend. Lines are crossed, and then backed off of. Divisions appear and expand. When they get back to Chicago, everyone, and especially Luke and Kate, have to deal with the consequences of what happened, what didn’t happen, and what could happen.

Swanberg is often identified with the so-called “mumblecore” movement — hyper-naturalized, improvised films about disaffected twentysomethings where little is said and less happens. Like Lynn Shelton with “My Sister’s Sister,” “Drinking Buddies” represents an attempt to move into more mainstream filmmaking, with bigger stars and more plotting, while still retaining the loose, authentic vibe of his earlier films.

In “Drinking Buddies,” I think the balance is just about perfect. He’s got a great cast at his disposal — Kendrick and Johnson (“The New Girl”) are total charmers, and I now have to completely reassess my opinion of Olivia Wilde. So often stuck playing “the girl” or “the other girl” in rigidly formulaic Hollywood movies like “The Change-Up,” she’s appealingly complex as Kate, flinty and funny but also kind of rudderless.

And Wilde and the other actors really seem to relish Swanberg’s approach, getting to say things that real people might actually say, communicating not with big speeches but with small moments. Swanberg’s shooting style makes us feel like we’re another person in the room, a fellow patron at the bar, bonding with these people even as we’re trying to suss out what they’re really thinking. And caring a lot about what will happen to them.