Overcome by the power of memory, Ann Lord (Vanessa Redgrave) reveals a long-held secret to her concerned daughters; Constance (Natasha Richardson), a content wife and mother, and Nina (Toni Collette), a restless single woman. Both are bedside when Ann calls out for the man she loved more than any other.

But who is this "Harris," wonder her daughters, and what is he to our mother? While Constance and Nina try to take stock of Ann's life and their own lives, their mother is tended to by a night nurse (Eileen Atkins) as she journeys in her mind back to a summer weekend some fifty years ago, when she was Ann Grant (Claire Danes)...

...a young woman who has come from New York City to be maid of honor at the high-society Newport wedding of her dearest friend from college, Lila Wittenborn (Mamie Gummer). The bride-to-be is jittery, and turns to her maid of honor rather than her own mother (Glenn Close) for support. Ann stays close to her friend, yet is even closer to Lila’s irrepressible brother Buddy (Hugh Dancy).

Unexpected feelings surge forth once Ann meets wedding guest Harris Arden (Patrick Wilson), a lifelong friend and intimate of the Wittenborn family. Ann's love for Harris will change her life, and those of her daughters, forever.