Seth Rogen and Rose Byrne return as married couple Mac and Kelly Radner, set to find a bigger home in a nicer neighborhood to live in after Kelly finds that she has another baby on the way. After putting down for their new abode, they find a buyer for their current one, but it's still in escrow, which, overly simplified for the purpose of this film, means that the buyer can swing by anytime within thirty days to inspect the house and can back out of the deal if things aren't up to snuff. The problem: a new, unaffiliated sorority, Kappa Nu, has moved in to take over the empty home previously used by the fraternity next door, built mostly on the notion that, unlike other sororities that aren't allowed to throw parties where they serve alcohol, they will do all of the drinking, raving and weed smoking they want, just like their male counterparts in fraternities do, without the overhead of being treated like "hos" by so-called rape-y frat boys.