Warren Schmidt (JACK NICHOLSON) is a 66-year-old former insurance salesman who's come to realize that retirement isn't all it's cut out to be. Now at home with his wife, Helen (JUNE SQUIBB), in Omaha, he tries to find some purpose in his life and eventually decides to financially support Ndugu Umbo, a young boy in Tanzania with whom he exchanges letters.
Then one day he comes home to find Helen dead and his life changes forever. After making all of the related arrangements, he then comes to the realization that he needs to make the best of his remaining time. It's not until he discovers that Helen and his best friend and former coworker Ray (LEN CARIOU), were more than just friends that he decides to set out across the country in the RV he and Helen had earlier purchased.
After hitting various spots and eventually forgiving Helen, he sets off for Denver where his adult daughter Jeannie (HOPE DAVIS) lives and is preparing to marry Randall Hertzel (DERMOT MULRONEY). He's a waterbed salesman and Warren thinks Jeannie can do much better than him, a point that further strains their already tenuous relationship.
Upon arriving there, he meets Randall's divorced parents, Roberta (KATHY BATES) and Larry (HOWARD HESSEMAN), and isn't overly pleased with the extended family into which his daughter is planning to marry. While still corresponding with Ndugu, Warren still tries to persuade Jeannie to change her mind. Yet, with the big day approaching, Warren must deal with the inevitable and eventually realize that his life has not been without purpose.