Jane Fairchild is a maidservant who finds herself working for the affluent Niven family during the tumultuous period between the wars. On the special occasion of Mothering Sunday, she is unexpectedly granted the day off to do as she pleases. To her astonishment, Paul Sheringham, the son of the prominent neighboring family, invites her to spend the day at his family home while his parents enjoy lunch with the Nivens and the Hobdays.
For years, Jane and Paul Sheringham have engaged in a clandestine affair since her arrival at the Niven estate. However, Paul is on the verge of marrying Emma Hobday, a woman from his social circle who was once unofficially betrothed to his late brother, James Sheringham, who perished in the Great War. Both Paul and Emma are conflicted about their forthcoming marriage, but societal expectations weigh heavily on them.
While at the Sheringham estate, the two lovers share a passionate encounter before Paul hastily departs to rejoin his family and fiancée for lunch. Left alone in the house, Jane wanders through the abode in a state of undress, taking in the opulence around her, indulging in food and drink before setting off on her bike.
As time moves forward, we find Jane transformed into a writer, now married to Donald, a philosopher she encountered while working in a bookstore. When Donald inquires about her journey to becoming a writer, she recounts her birth and the gift of a typewriter as pivotal moments, choosing to withhold the third.
This third moment takes place on a Mothering Sunday following her rendezvous with Paul. Jane unexpectedly encounters Godfrey Niven, who reveals the tragic news of Paul’s death in a car accident. He asks Jane to accompany him to Paul’s home, where he subtly implies he wants to ensure the space remains free of anything that could further distress their family. Upon arrival, they discover the maid has returned early, reporting that she has meticulously cleaned Paul's room and found no note.
In a later timeframe, we see Jane and Donald grappling with devastating news: Donald has been diagnosed with an inoperable brain tumor. He contemplatively suggests that his impending death might inspire her to craft her finest work, though he mourns the fact that he will not be around to read it. As he nears the end, Donald implores Jane to reveal the truth behind the third incident, but she chooses instead to profess her love for him.
Years later, now an older woman, Jane is approached at her residence by journalists eager to discuss her recent accolade—a prestigious literary award. Unfazed by the attention, she dismisses them, noting that she has already collected all available literary honors, and then returns to her typewriter, embodying her enduring passion for writing.
