Plot summary

Hortense Cumberbatch, a black optometrist in London who was adopted as a child, has chosen to trace her family history after the death of her adoptive mother. Despite being warned by public officials about the troubles she could face by tracking her birth mother down, she continues her investigation and is surprised to learn that her birth mother is white.The woman in question, Cynthia Purley, works in a cardboard box factory and lives in East London with her other illegitimate daughter Roxanne, a street sweeper; the pair have a tense relationship. Cynthia's younger brother Maurice is a successful photographer who lives in the suburbs with his wife Monica. The couple also experience domestic difficulties due to Monica's often distant temperament. Later scenes reveal that she suffers from severe menstrual cramps. Cynthia and Monica have never liked one another: Monica regards her sister-in-law as self-pitying and overly hysterical, while Cynthia deems Monica greedy and snobbish. For this reason, Maurice rarely sees Cynthia and Roxanne despite not living particularly far from them, but he and Monica both look forward to celebrating their niece's upcoming 21st birthday. When Maurice pays Cynthia a surprise visit, she breaks down in tears, berating her brother for his long absence. Before leaving, Maurice gives her money to pay for repairs on the house and tells her of his and Monica's wish to hold a barbecue for Roxanne's birthday.Roxanne is revealed to have a boyfriend, Paul, whom Cynthia has never met. This leads to an argument between mother and daughter; Roxanne storms out, leaving Cynthia in tears. Shortly thereafter, Hortense rings Cynthia and starts to enquire about "baby Elizabeth Purley", whom she says was born in 1968. Cynthia realizes that Hortense is the daughter she gave up for adoption as a teenager and hangs up the phone in distress; persevering, Hortense rings Cynthia again and eventually manages to persuade her to meet her. When they come face to face, Cynthia, not expecting Hortense to be black, insists that a mistake has been made with the birth records. Hortense convinces Cynthia to look at some documents pertaining to Hortense's birth. Cynthia remains convinced that Hortense is not her daughter until, suddenly, she retrieves a memory and begins to cry, stating that she is ashamed. Hortense then asks who her father was, to which Cynthia replies, "You don't wanna know that, darling." The pair continue to converse, asking questions about one another's lives.Soon Hortense and Cynthia have struck up a friendship; Cynthia, who is not in the habit of going out, suddenly finds herself doing so frequently, catching the attention of Roxanne, who is confused by her mother's secrecy. On one of their meetings, Cynthia mentions to Hortense Roxanne's birthday party. She later asks Maurice if she can bring a "mate from work" to the barbecue; when he says yes, she relays this information to Hortense, who, despite her reservations, agrees to attend and pose as Cynthia's colleague.On the day of the birthday party Monica makes an effort to be welcoming, but nonetheless she and Cynthia are unable to resist making passive-aggressive comments towards one another. During the barbecue Hortense evasively answers the many questions that are put to her by the other guests. The party moves inside due to rain. While Hortense is in the bathroom, Cynthia, who has become increasingly nervous, reveals that she is Hortense's mother. Roxanne dismisses this claim, assuming that she has had too much to drink, but when Monica inadvertently confirms it as true, she is furious and storms out of the house. Maurice attempts to pacify the situation by confronting Roxanne at a nearby bus stop, and he and Paul manage to convince her to hear her mother out. Meanwhile, Cynthia and Monica quarrel. Cynthia says that Monica should try bringing up a child on her own, to which Monica, though visibly upset, says nothing. When Roxanne, Maurice and Paul return, Cynthia explains matters: she fell pregnant at fifteen and was sent away by her father; after the adoption she never expected Hortense to seek her out. Cynthia proceeds to berate Monica, and Maurice, coming to the latter's defense, reveals that she is physically incapable of having children. He loses his temper, exhorting those present to "share [their] pain" instead of harboring resentments. He praises Hortense for having the courage to seek the truth. Cynthia then explains that Roxanne's father was an American medical student vacationing in Benidorm whom she met at a pub. One morning, Cynthia awoke and he had gone. Hortense again enquires as to the identity of her father. Cynthia replies, "Don't break my heart, darling."After a while things have calmed down and Hortense pays a visit to Cynthia and Roxanne at their home. When Hortense reveals that she always wanted a sister, Roxanne says that she would be happy to introduce Hortense as her half-sister notwithstanding the long explanations that it would entail.