Mac Radner and his Australian-born wife Kelly are a young couple with an infant daughter, Stella. The restrictions of parenthood make it difficult for them to maintain their old lifestyle, which alienates them from their friends Jimmy Blevins and his ex-wife, Paula. One day, the couple finds out that Delta Psi Beta, a fraternity known for their outrageous parties, has moved into an adjacent house. The fraternity's leaders, Teddy Sanders and Pete Regazolli, aspire to join Delta Psi's Hall of Fame by throwing a massive end-of-the-year party.
Mac and Kelly are trying to sell their home with the arrival of another baby. A couple, Eric and Jessica Baiers are looking to buy; the realtor tells Mac and Kelly that their house is in escrow for 30 days. Meanwhile, Mac's friend, Jimmy, and his once-again wife Paula are also expecting a baby. At the Phi Lambda sorority, Shelby, a freshman, learns that sororities are not allowed to host parties, and can only attend frat parties. Shelby goes to a frat party and meets two other freshmen, Beth and Nora. They are disgusted by the sexist and perverse nature of the party and leave. Bonding over their dissatisfaction, the trio decides to set up a new sorority, Kappa Nu, to host their own parties.