Suzette (GOLDIE HAWN) is a middle-aged bartender at an L.A. club where she's seen all sorts of rock n' roll history over the decades. When her much younger boss fires her, the former groupie sets out to find her former friend and fellow groupie, Vinnie (SUSAN SARANDON), who now lives in Phoenix.
Unfortunately, she doesn't have enough money for gas and thus agrees to give a ride to Harry (GEOFFREY RUSH), a neurotic and obsessive-compulsive writer, in exchange for him paying their way. He's also headed to Phoenix to fulfill a promise he made long ago.
Upon arriving there, Suzette sets off to find Vinnie, but instead meets her teenage daughter, Hannah (ERIKA CHRISTENSEN), a seemingly straight-laced high school senior who's having a bad reaction to some acid she's taken at the prom. Suzette drives Hannah home where she then meets Vinnie who now goes by the name Lavinia.
Now married to Raymond (ROBIN THOMAS), a successful lawyer, with another teenage daughter, Ginger (EVA AMURRI), at home, Lavinia is the complete opposite of the still free-spirited Suzette who hasn't changed much since their earlier groupie days. She doesn't want anything to do with Suzette, especially when she figures out she needs money.
Yet, Suzette's presence eventually begins to bring out Vinnie's long-since repressed youthful exuberance, and her family isn't sure what to make of her sudden change. As the two become reacquainted and Harry sets out to set things straight with his father, it's uncertain what will happen with the former "Banger Sisters."