In the novel The Moving Finger, Megan Hunter is a 20 year old girl living in Lymstock, along with her mother Mona Symmington, her stepfather Richard Symmington, her two younger half-brothers and the nursery governess Elsie Holland. Her biological father, Mr (or Captain) Hunter, is not talked about much. It is believed that he went to prison for blackmail.
Megan is described as a "tall awkward girl", and although she is twenty, she looks more like a sixteen-year-old. She has "a shock of untidy brown hair, hazel green eyes, a thin bony face, and an unexpected charming one-sided smile". She often has holes in her stockings. When she was at school, she used to ink her legs so that Miss Batworthy, the mistress who looked after the students' mending, would not notice that she had not mended her stockings.
Megan is feeling like the third wheel in the family. She believes that the family is complete without her and that her mother prefers to only be around her stepfather and her two brothers.
Mrs Symmington felt that Megan was a difficult child, and considered her young for her age, and still quite a child. She said that she had tried to find something for Megan to do, such as designing and dressmaking, or shorthand and typing. Aimée Griffith also felt that Megan needed something to do, and tried to get her involved with Guides. However, Megan herself seems to think she had no skills, and she had no interest in joining the Guides. She also believes that everyone thinks she is stupid, and they do not know that she knows what they are like, and hates them.
When Megan meets Jerry Burton and his sister Joanna Burton, she immediately gets on very well with them. After the death of Mrs Symmington, they invite her to stay with them at Little Furze for a few days. Megan enjoys staying with them, but after Aimée Griffith tells her that people are saying that Elsie Holland intends to become the next Mrs Symmington, she decides to go home.
Megan later discovers the body of Agnes Woddell in the cupboard under the stairs. She is greatly distressed by this, and telephones to Jerry, asking him to come.
When Jerry goes for his monthly appointment with Marcus Kent in London, Megan sees him off at the train station. Jerry gets the idea that he would like to take her to London and outfit her from head to toe. He brings her to Joanna's dressmaker, and asks Mary Grey to give her a makeover. They then go for cocktails, dinner, and dancing.
Jerry realises that he has fallen in love with Megan, and asks her to marry him, but she turns him down, saying that she does not love him, and is not the sort of wife for him.
Towards the end of the novel, Miss Marple asks Megan to help set a trap for the murderer. Megan asks the murderer for money, saying that she saw what was done to her mother's cachet on the day she died. The murderer later tries to kill Megan by drugging her and putting her head in the gas oven. Jerry pulls her out and turns off the gas, while the police apprehend the murderer.
When Megan wakes, she tells Jerry about a letter she had begun writing to him the night before, in which she says that she does love him after all.
At the end of the novel, Jerry and Megan get married, and buy Little Furze.