Greta Gerwig, left, and Lola Kirke in Mistress America (Fox Searchlight Pictures)

Viewers who loved Frances Ha may be expecting more of the trials and tribulations of the 20-something from this latest collaboration between director Noah Baumbach and his cowriter/star Greta Gerwig. But Mistress America veers off in a different direction, keeping the quips coming fast and furious but sacrificing emotional authenticity.

Tracy (Lola Kirke) is in her first semester of college in New York City and loathing every minute of it: the hateful roommate, the pretentious classes, the elitist literary society that passes on her short story. Baumbach excels at portraying loneliness and alienation with an utter dreariness that rings true. Gray-tinged scenes of Tracy receiving pointed writing criticism in a dorm room or a starkly lit shot of her eating alone in the dining hall are uncomfortably realistic.

Things start to look up when Tracy meets Tony (Matthew Shear), a fellow literary society reject. Predictably, however, before anything remotely salacious happens, Tony’s got a girlfriend, the uber-jealous, perpetually dour Nicolette (Jasmine Cephas-Jones), and Tracy’s once more on the outside looking in. When her mother, who’s about to remarry, suggests that Tracy call up Brooke, her soon-to-be-stepsister, Tracy’s initially skeptical but finally gives in.

Enter Brooke (Gerwig), who saunters down a flight of stairs at Times Square into Tracy’s life. Everything about Brooke is dazzling in comparison with Tracy’s up till now lukewarm existence: her clothes, her knowledge of the best nightspots, her savoir faire, and her explosively effervescent stream-of-consciousness style of speech. Like many men before her who have been roused out of the darkness by a free-wheeling, blithe spirit, Tracy uses her new companion as a muse; she even begins a new short story based on Brooke the morning after meeting her. Brooke just as readily takes to the role of a sexy and hip Auntie Mame, doling out life lessons over cocktails and taking the green college student on a heady whirlwind tour through the city.

However, it’s soon clear that Brooke won’t easily be pigeonholed into a familiar manic pixie dreamgirl trope. Perhaps manic pixie nightmare girl is more apt. In the light of day, the enchantingly imperious eccentric is quickly revealed to audiences as an air-headed and flighty user. Gerwig manages to make Brooke’s utterly self-absorbed nature hilarious, and viewers will be laughing (and cringing as they hope for sweetly vulnerable and too easily charmed Tracy to make a run for it). Likewise, Kirke’s portrayal of Tracy rings true. Audiences who saw Gone Girl may not even recognize Kirke, who played a streetwise, not easily fooled tough. Here Kirke makes a 180-degree turn, effortlessly playing an intelligent but ill-at-ease young woman just coming into her own, trying on identities like ill-fitting costumes.

Things that once seemed too good to be true come crashing down: Brooke’s locked out of her impossibly trendy apartment, and her plans to open a restaurant in Brooklyn fall through due to lack of funding. A trip to Brooke’s psychic adviser sends the pair off to see Mamie Claire (Heather Lind), a former friend who supposedly cheated Brooke out of a lucrative idea for a clothing line, to reclaim what’s rightfully Brooke’s (or, seen through a less optimistic light, to beg for cash). The wacky quotient ratchets up: Tracy and Brooke pile into Tony’s car, with Nicolette along for the ride, for a trip to Greenwich, Connecticut. The introduction of Mamie Claire and her husband, Dylan (the always watchable Michael Chernus), as an affable hedge-fund type still yearning for his stoner days, adds further humor, but eventually, when the laughs wear thin, viewers will wonder what the point is.

As the hilarity winds down, it’s not clear what, if anything, is holding the film together. Though in the final act, Baumbach and Gerwig clumsily attempt to convey a message of friendship and the importance of staying true to oneself, it feels tacked on. Mistress America makes for a fun romp, but ultimately it’s the cinematic equivalent of a night with Brooke: an exhilarating adventure but an empty one.