Lucy (Mira Sorvino), a hot mess in a minidress and spike-heel boots, shows up in Manhattan, yappy little dog in tow, hoping to surprise the married guy with whom she's apparently having an affair. When he proves less than thrilled by this unscheduled visit, Lucy activates plan B, showing up unannounced at the crazy-posh loft overlooking Union Square where her sister, Jenny (Tammy Blanchard), lives and runs an organic-food business with her straitlaced fiancé Bill (Mike Doyle). The sisters haven't spoken in years, and the mystery of what went wrong between them—to the point that Jenny refused Lucy's Facebook-friend request!—is held out for much of Union Square as a big reveal. Set mostly in the loft over a three-day span culminating in a narratively useful awkward Thanksgiving dinner, the sixth feature from director Nancy Savoca (Dogfight) often feels like an acting exercise documented on video for teaching purposes—lots of unnecessary histrionics and ostentatious zooms, with both the story and the improv-like dialogue predicated on contrivances and glaring improbabilities ("You're trying to pass," sniffs one proudly uneducated character, dropping the keywords of identity politics a few scenes after having confused mesclun greens for mescaline). That said, there's a lovely chemistry between Blanchard and Sorvino, whose bond as sisters is most convincing when they're not speaking.