‘Mistress America' funny and shrewd

Greta Gerwig has the title role in the manic and maniacally funny “Mistress America,” a chatty, shrewdly observant comedy about a New York/social media “type” anybody with a cell phone will recognize.

Tracy (Lola Kirke of “Gone Girl”) certainly has. She’s a frustrated writer-wannabe who hasn’t cracked the literary circles of elite Barnard College. But her mother (Kathryn Erbe) is about to marry a guy with a 30 year-old daughter living in New York. That’s how Tracy meets Brooke (Gerwig).

Brooke is a blonde whirlwind of positivity, a self-educated self-described polymath. She coaches a spin class, tutors middle school kids, gets up on stage and sings with a band and is well on her way to launching a conceptual restaurant she will call “Moms’, possessive.”

She flits from passion to passing fancy, never quite following through but supremely confident in all she does. Her special skill? Drawing a crowd.

“I keep the hearth. That’s a word, right? Hearth?”

Tracy is “Baby Tracy,” to Brooke. And the lonely but cute coed is utterly smitten with this Holly Golightly she’d love to have breakfast at Tiffany’s with. Brooke isn’t just a cool older-sister-to-be. She’s material, fodder for a writer.

“Her youth had died,” she narrates into a short story, “and she was dragging around the rotting carcass.”

In 80 or so brisk minutes, Brooke consults her spirit advisor, gets locked out of her “zoned commercial” Times Square apartment, faces the end of her dreams and hilariously confronts a nemesis (Heather Lind) she insists stole her cats, her future husband and her first big business idea from her.

Gerwig, who helped invent the talk-and-nothing-but “mumblecore” genre, has become the muse to director Noah Baumbach (“While We’re Young”), and this film is a fusion of their styles. Brooke is a fascinating, exhausting character with a dizzy patter, which she’s happy to share with Tracy and her college freshman peers.

“There is no ‘cheating’ when you’re 18! You should all be touching each other all the time!”

With all its Baumbach and Gerwig mumblecore underpinnings, “Mistress America” is Baumbach’s version of a Wes Anderson comedy. Strip away the gaudy colors, snippets of animation and earnest loopiness and you get lots of witty banter, breathlessly delivered by an engaging cast of believable and unbelievably glib characters.

And Brooke? We don’t have to know her to “know” her. There she is on Gawker or Wonkette or Perez Hilton’s websites, flighty, attention-grabbing and cute. For just as long as she can drag that carcass of her youth around with her.