Mistress America is not a new comic-book movie, although Greta Gerwig, who stars, has a kind of stand-tall, hands-on-hips superhero vibe about her.

Brooke Cardinas, the freewheeling New Yorker she plays in the film cowritten with her director and partner-in-life, Noah Baumbach, is impervious to setbacks or crises. Ricocheting around the artsy quadrants of the city, she's full of great ideas and grand ambitions, but not very good at implementing them.

That isn't going to stop her from trying.

A screwball comedy about female friendship and intellectual-property theft (well, not quite, but we'll get to that), Mistress America breathlessly tags along as Brooke makes wild gesticulations and snappy pronouncements, by way of mentoring the decade-younger Tracy Fishko (Lola Kirke), a shy suburbanite newly installed in the freshman dorms at Barnard.

Brooke and Tracy are soon to be stepsisters - Tracy's mom is set to marry Brooke's dad - so why not teach the kid from the sticks a thing or two about city life?

Full of breakneck, Preston Sturges-y dialogue (Brooke calls people "Squirt" and "Rich Boy" - there's a lot of jaunty name-calling), Mistress America has a serious, poignant side, too.

Kirke's Tracy is a little sad, a little lonely, and has more than a little yen to be a writer. A rejection from the college's clubby literary society sets her off: She's determined to write a story worthy of publication. So, as she tags along with Brooke to dances, dinners, and late-night powwows back at Brooke's loft, Tracy starts taking notes (and a few of Brooke's tchotchkes, too).

As her manuscript begins to take shape, a question starts to push its way onto the screen: What are the ethics behind appropriating details and plot from someone's life for your made-up "fiction"? Does art necessitate betrayal?

Although Mistress America is very much a New York movie, full of references to couture, pop culture, boutique hotels (to Antigone and Faulkner, too), its comic centerpiece is a brazen assault on a country compound.

Brooke drags Tracy and a couple of unwitting college dorks (one of them has a car) to Connecticut, where Brooke's "nemesis," Mamie-Claire (a deadpan Heather Lind), lives with the man (Michael Chernus) and the cats she stole from Brooke.

The mission is to get investment money for a restaurant Brooke wants to open, and her ex-beau, now Mamie-Claire's husband, has a few million lying around. It's a pitch meeting that turns into a free-for-all, orchestrated with Bringing Up Baby flair - the classic 1938 Howard Hawks romp featuring a country house in, yes, Connecticut.

"Hi ho, Greenwich!" Tracy declares, the decision made that the duo need to proceed posthaste to the Nutmeg State.

Hepburn couldn't have delivered the line any better.