Harry Sanborn (Jack Nicholson) is a New York music mogul with a libido much younger than his years. He has the world on a string -- and a string of beautiful young girlfriends to prove it. During a romantic rendezvous with his newest girlfriend, Marin (Amanda Peet), at her mother's Hamptons beach house, Harry develops chest pains and eventually winds up being nursed by Marin's reluctant mother, Erica Barry (Diane Keaton) -- a successful, divorced New York playwright. In the process, Harry develops more heart pangs -- the romantic kind -- for Erica, a woman who is finally right for him in every way.