Jane (MERYL STREEP) is a middle-aged woman who feels that she's finally come into her own. Yet, while her professional life has been a success owning and running a popular bakery, her love life hasn't actually been terribly active, a point discussed with her best friends including Joanne (MARY KAY PLACE), Trish (RITA WILSON) and Diane (ALEXANDRA WENTWORTH). They're concerned that ever since her divorce from her lawyer husband, Jake (ALEC BALDWIN), a decade earlier, she hasn't dated many men.
Then again, she's been busy raising their three kids. Lauren (CAITLIN FITZGERALD) is engaged to Harley (JOHN KRASINSKI), while Gabby (ZOE KAZAN) is now moving out on her own. And Luke (HUNTER PARRISH) is about to graduate from college, meaning the family, including Jake, have gathered at a hotel for the big ceremony. It's there that Jane and Jake, after a few too many drinks and some dancing, end up in bed together.
She's horrified, but he's ecstatic, not only because he's grown tired of fertility treatments as his younger wife, Agness (LAKE BELL), wants another child to join Pedro (EMJAY ANTHONY) who was fathered by another man, but also because he never really stopped being in love with Jane.
The only problem is, she's developed a newfound attraction toward Adam (STEVE MARTIN), a mild-mannered and divorced architect who's working on redesigning and expanding her house. From that point on, and as she carries on her fling with Jake, Jane must decide if she wants to go back with him or start something fresh and new with Adam.