Ever since being entranced by young girls attending a wedding at New York City's Plaza Hotel, Liv (KATE HUDSON) and Emma (ANNE HATHAWAY) have dreamed of having their respective big days there on a Saturday in June. While middle school teacher Emma is something of a pushover -- always allowing coworker Deb (KRISTEN JOHNSTON) to get her to cover for her -- and thus patiently awaits live-in boyfriend Fletcher (CHRIS PRATT) to propose, lawyer Liv is more direct with her boyfriend, Daniel (STEVE HOWEY), demanding an engagement.
That's especially true after Emma ends up engaged first, with Liv then joining her, and the two waste no time in meeting with legendary wedding planner Marion St. Claire (CANDICE BERGEN). The two young women are ecstatic and plan to be each other's maid of honor, but a snafu results in both being scheduled for the lone opening at the Plaza for a June wedding.
And from there, their friendship devolves into a competitive affair where both strive to grab that date and sabotage the other's nuptials. Accordingly, they need to find new matrons of honor, but have a hard time doing so, with Emma reluctantly asking Deb to be hers. Since Liv's brother, Nate (BRYAN GREENBERG), will be giving her away, she's stuck with asking her personal assistant at work, Kevin (MICHAEL ARDEN), to do the duties. With their big day quickly approaching, the two women pull out all of the stops to try to undermine the other's wedding.