David and Paige Watling (Hugh Laurie and Catherine Keener) and Terry and Cathy Ostroff (Oliver Platt) are best friends and neighbours living olt Orange Drive in suburban New Jersey. Their comfortable existence goes awry when prodigal daughter Nina Ostroff (Leighton Meester), newly broken up with her fiance, returns home for Thanksgiving after a five-year absence. Rather than developing an interest in the successful son of her neighbours, Toby Walling (Adam Brody), which would please both families, it is her parents best friend David who captures Ninas attention.

When the connection between Nina and David becomes undeniable, everyones lives are thrown into upheaval, particularly Vanessa Wallings (Alfa Shawkat), Ninas childhood best friend. It is not long before the ramifications of the affair begin work on all of the family members in unexpected and hilarious ways, leading everyone to reawaken to their lives and reassess what it means to be happy.