Georgina "Georgy" Parkin is a 22-year-old Londoner with musical talent, well-educated, and an engaging, unpretentious character. She has an inventive imagination and loves children. At the same time, she is overweight, believes herself to be plain, dresses haphazardly and is incredibly naïve on the subjects of love and flirtation, having never had a boyfriend. Her parents are live-in employees of James Leamington, a businessman who is in a loveless, childless marriage with the sickly Ellen Leamington.
Leamington, who has watched her grow up and treated her as a second daughter, begins to feel more than paternal toward her. On his 49th birthday, he offers a legal contract: he will provide Georgy with the luxuries of life in exchange for becoming his mistress. Georgy sidesteps the proposal, choosing independence instead.
Meredith is the beautiful violinist in an orchestra who shares a flat with Georgy. While she goes on dates with various men, Georgy entertains her boyfriend, Jos Jones, on whom she has developed a crush.
Meredith discovers that she is pregnant by Jos, and they decide to marry, though she tells him that she has previously aborted two of his children and only wants the marriage because she is "bored." After the wedding, Jos moves in with Meredith and Georgy, becomes disillusioned with Meredith, and finds himself attracted to Georgy.
Georgy uses Leamington's interest in her to convince him to buy several expensive items for the baby, and Ellen dies suddenly, but Georgy does not sign Leamington's contract.
In the midst of an argument with Meredith over her cavalier attitude toward the pregnancy, Jos kisses Georgy and tells her that he loves her. Georgy flees the apartment, and Jos follows her into the streets of London, shouting his love for her. The two return to the flat, where they have sex, after which Peggy, a neighbor, tells Jos that Meredith has gone into labor, and he and Georgy go to the hospital.
Although Georgy feels guilty, she continues her affair with Jos while Meredith is in the hospital. Meredith has no interest in her daughter, Sara, and has tired of Jos, announcing that she plans to put the child up for adoption. When Georgy sees Sara, she is smitten.
Georgy and Jos bring Sara back to the flat. It quickly becomes clear that Georgy cares more for the child than for Jos, and their relationship ends when Jos tires of paternal responsibilities and abandons Georgy and Sara. Now that Georgy is the sole caregiver of a child to whom she has no blood ties, Social Services wish to remove Sara from her care.
Leamington has been following the developments. When he mentions modifying his contract to accommodate the recent changes, Georgy, seeing an opportunity to keep Sara, gets him to propose marriage. As the newlyweds are chauffeured away from the church on their wedding day, Georgy ignores Leamington, devoting all of her attention to Sara.
