While Lola Kirke’s Tracy navigates a prematurely weary college scene, searching for inspiration and the vivacious lifestyle New York offers up in the movies, Greta Gerwig’s Brooke is tumbling on stage to front hip bands in even hipper nightclubs, freelancing, writing, moving and shaking her way back to her impossibly chic – yet illegal – Times Square apartment every night. “I got off the bus. I thought this was the cool place to live. It’s Times Square!” she explains when these two opposites collide for the first time.

Perhaps if more actors were entrusted with the task of co-writing their roles we’d be treated to more Brookes on screen. Gerwig’s turn as the rambunctious socialite – more interested in discussing her ideas than acting on them while launching head first into everything her metropolitan territory has to offer – is a masterstroke. She cements herself as one of cinema’s most exciting comediennes in Mistress America, periodically robbing the limelight from every scene until we’re suddenly in the midst of a truly incredible set piece.

The film’s middle third treats us to a beautifully choreographed exchange in a suburban house, neatly whipping together the key players in Brooke’s tale of woe-cum-blissful acquired wisdom. Driven there by a spirit talker, but literally driven by Tracy’s unrequited crush and his perennially jealous girlfriend, this mini-road trip and the ensuing screwball section – which is more akin to a tightly-wound stage play – is a maniacally funny, impeccably written thunderstorm of ideas, observations and choreography.

The unbridled zest and ambiguity of life at both ends of twenty is a common theme for Noah Baumbach and one that speaks volumes to audience members of the requisite age in Mistress America. An unquenchable desire for validation is dutifully apparent in Tracy, whose performance enables Gerwig to shine rather than allowing her character to be trampled. She desires tenure in an exclusive literary club of students she regularly denounces while juggling whichever zeitgeist her sister-in-law-to-be is rambling on about. In short, she’s just as lost as Brooke, but at the ‘right’ side of twenty, she soon discovers the simplest of life lessons.

Special mention goes to Matthew Shear – the object of Tracy’s naked desires and submissive player in her college landscape. His Michael Cera-esque delivery and genuine zest for ideas and creativity gifts him naïve adorability, simultaneously spliced with his petulant girlfriend, whom he loves against all human comprehension. His snapshot contributions to the house scene are truly a joy.

The film does veer on the side of being too contrived at points, particularly before the whip-smart set piece that also serves to deliver the vehicle for its final third. This conflict is perhaps a little far-fetched given what we already know about Brooke’s untroubled demeanour, but it’s by no means a deal-breaker. And even though some of its back-and-forth scenes seem a touch unspontaneous – a quality our heroines’ relationship relies upon – Mistress America rightly deserves its burgeoning reputation as one of the year’s funniest romps.