Adam Driver aside, the first member of the cast of “Girls” to bust out on the big screen has been Allison Williams, so good as the treacherous “post-racial” viper girlfriend in “Get Out.” But Zosia Mamet, in “The Boy Downstairs,” is the first “Girls” veteran to stake her claim in the movies as, you know, a girl — a character who might have stepped right off of the show. Diana, the crestfallen romantic she plays here, is far from a carbon copy of Shoshanna, her eager antic flake on “Girls.” Mamet, in the movie, sports a bedraggled mop of blonde-hair-with-roots parted in the middle, which brings out her deeply serious eyebrows, and the confusion she radiates is no longer intrinsically comic. It’s the mixed-up emotion of someone who has used her freedom to make the enlightened — and wrong — choice. Mamet has a quick, spry reaction time and a gently forlorn focus that holds the screen, and she holds this movie together.

“The Boy Downstairs,” while it leans more toward Manhattan than Brooklyn, occupies the same basic New York demimonde of desperate but upscale “creative” strivers that “Girls” did. Yet when compared to the show (which it’s almost impossible not to do), the movie is a bit of a paradox. Written and directed by Sophie Brooks (her first feature), it’s a dawdling-but-not-too-dawdling, crisply shot semi-mumblecore romantic comedy, and taken on its own terms, it works fine. Yet it’s just the sort of earnest indie trifle that “Girls” was influenced by and transcended. The box-office prospects for this kind of movie are more and more limited, not because it’s bad (it isn’t), but because the audience for it has basically moved on.

Diana needs an apartment, and after her kooky best friend, Gabby (Diana Irvine) — or is Diana the kooky best friend? Let’s call both of them kooky best friends — hooks her up with a real-estate broker, she finds a second-floor apartment in a brownstone rented out by Amy (Deirdre O’Connell), a free-spirited widow who owns, and lives in, the building. It seems an ideal arrangement, even if the economics remain a little pie-in-the-sky. Diana has designs on becoming a fiction writer, which is starting to sound a bit like saying that you want to be a poet. If you choose to write fiction, fine, but the overlap between that and the banality of actually making a living has become infinitesimal-verging-on-invisible. Diana earns her keep by working at a bridal shop, a job that the movie, to its credit, never suggests is any reflection of some hidden princess-fantasy side of her.

Yet she does, in her way, need to be rescued. It’s fate that performs the service: Just as Diana is moving into her airy new flat, she sees a familiar face emerge from the ground-floor apartment. It’s Ben (Matthew Shearer), her ex from a few years ago, who looks like the world’s cuddliest chess player. But to judge from the way he reacts to her — a blend of soft-spoken gentle passivity, which seems his basic nature, and extreme underlying aggrievement — it’s clear that something happened that wasn’t pretty.

It’s all a set-up, a concept, an indie-going-for-mainstream hook: What if you learned that your ex, by complete coincidence, lived in the apartment below you? (Actually, it’s also a sitcom.) And what if you discovered that Meg (Sarah Ramos), the girlfriend who replaced you, is the same WASP-snob real-estate broker who turned up her turned-up nose at you while helping to find your apartment? And what if all this makes you realize that you still wish you were with the ex? Would you play the crumpled wallflower? Attempt to make friends? Spy? Stalk?

Diana tries all of the above, and the reason we’re mildly intrigued, rather than annoyed, is that the film keeps flashing back to the early bloom of their relationship, and it’s lovely and convincing. The question of what went wrong hangs over every scene, and the answer turns out to be very “Girls”-like: a breakup that arose less out of betrayal than out of circumstances that added up to a betrayal of perfection. Is this a millennial problem — the expression of a too pure and indulged generation? In “The Boy Downstairs,” it sure looks that way. Yet here, it should be said, is a love story with an original conflict: an issue of travel, visas, and practicality that masks the underlying issue — the right, and the hunger, of women to roam the way that men once did.

There are good scenes, like Diana and Ben’s breakup, which has a lifelike crash of sadness, guilt, anger, and something less rational, and a couple of needlessly broad ones, like Diana’s first meeting with Ben’s “Look at us, we’re so Jewish!” parents. Mostly, there’s Zosia Mamet, with her quizzical charisma, proving yet again that there’s more to this girl than meets the eye.

Film Review: ‘The Boy Downstairs’

Reviewed at Tribeca Film Festival, April 24, 2017. MPAA Rating: PG-13. Running time: <strong>91 MIN.</strong>

  • Production: A Cliffbrook Films, Motion Picture Capital, Boy Downstairs Production prod. Producers: Dan Clifton, David Brooks, Leon Clarence. Executive producer: Paul Brooks.  
  • Crew: Director, screenplay: Sophie Brooks. Camera (color, widescreen): Stefan Weinberger. Editor: Matthew Friedman.
  • With: Zosia Mamet, Matthew Shear, Deirdre O’Connell, Sarah Ramos, Diana Irvine, Arliss Howard, Deborah Offner, David Wohl.