Molly Gibson, whose mother has long ago died, is brought up by her father Dr. Gibson. At the age of 17, Molly visits and immediately befriends the Hamleys, her neighbors, especially she and the youngest son Roger Hamley, studying in Cambridge, become good friends. This is when Dr. Gibson tells his daughter of his upcoming marriage to Hyacinth Kirkpatrick, a widower who also has a daughter around Molly's age, Cynthia.
It is revealed that Cynthia is also secretly engaged to Mr. Preston ever since she was 15 years old. When she tries to break off that engagement, Preston is reluctant to let her go or give her back her letters. After a visit to London, Cynthia also breaks off her engagement to Roger who is on an expedition in Africa. Osbourne's health decreases quite severely. Fearing his father's reproach, he still cannot tell him of his marriage to a French woman or his having a child.
Cynthia and Preston have a bitter row and Molly promises to help her escape from him.
Gibson house is in shock following Osborne's death. Can Molly still win Roger's heart?
Documentary included in the DVD release
Documentary about the making of the series.