"Union Square" is the setting for an unexpected reunion between two estranged sisters, one on the verge of getting married, the other on the verge of a nervous breakdown. Lucy (Academy Award(R) winner Mira Sorvino) attempts to shop for discount clothes while anxiously talking on her cell. When the news is not what she wants to hear, she has a complete meltdown. Unsure of her next move, she has an idea. Suddenly, Lucy finds herself somewhere she's never been: her younger sister Jenny's (Tammy Blanchard) loft apartment off Union Square. Jenny is stunned to see Lucy on her doorstep and, what's worse, unable to keep her out. Jenny has little time to prepare her fiance, who she's kept in the dark about her family's tumultuous upbringing in the Bronx, for her sister's excessive behavior. Lucy tries to update Jenny about their mother and when the news is not what Jenny expects to hear, she's left wondering just what else could possibly happen to disrupt her ordered life...that is, until Lucy delivers even more surprises.