Greta Gerwig stars in Noah Baumbach's 'Mistress America'

THERE'S A shocking and funny scene in "Mistress America" involving high school classmates meeting by chance at a bar, where one dredges up long-ago bullying.

It's a brief bit, almost a non-sequitur in the movie's larger scheme of things, but it sticks with you for the way it takes a familiar situation and blows it up, asking:

What's the statute of limitations on mean girls?

When does that grudge you're carrying start to look like a masochist's grumpy badge?

And can't you see that people are trying to enjoy a drink?

The scene and the movie are written by "Mistress America" star Greta Gerwig, and if the sequence flatters her, so what - Gerwig has addressed the problem of limited roles for women by writing her own.

She wrote and acted her way to a Golden Globe nomination in "Frances Ha," deploying a sort of wifty, Teri Garr charm to the coming-of-age role of a vulnerable girl taking on the big city and mostly losing.

Cusp-of-30 Brooke, the woman she's created for herself in "Mistress America," is a different breed. She has confidence to burn, but not money. Energy to spare, but little focus. Brooke is a personal trainer, interior decorator, entrepreneur - currently pitching investors on an idea for a restaurant.

She's either destined for success or delusional, perhaps does not know herself, and in any case is entirely fascinating to the shy college freshman Tracy (Lola Kirke) pulled into her orbit.

"Mistress America" is a loose collection of their adventures, with Brooke showing Tracy the ropes: first the basics of surviving/thriving in Manhattan, then pulling her (and an expanding entourage) on a trip to Connecticut to confront an old boyfriend who also may be a potential investor.

Gerwig gives herself many good scenes, but she's a generous writer who tells the story from the perspective of Tracy, a nicely drawn portrait of a bright young woman whose self-confidence does not yet match her talent.

And there is an unusual amount of attention lavished on characters, even minor ones. Gerwig and director Noah Baumbach conceived "Mistress America" as a tribute to the screwball comedies of old, giving the movie a manic, theatrical fizz - characters running in and out of frame, dialogue coming in volleys.

"Mistress America" culminates with a modernized drawing-room scene - Brooke and company (mostly college kids) crashing a suburban women's reading club.

The scene, again, is remarkable for the way it upends expectations. Potential antagonists end up getting along, and why not? Why wouldn't Columbia literature and writing students hit if off with hyper-educated suburban mothers who've channeled their overqualifications into book group?

Gerwig and Baumbach know their characters and the cultural landscape they inhabit, and they've adhered to a hallmark of the comedies of old: brevity.

Their homage is all of 86 minutes.

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