At the beginning of the novel, Carol and her brother Raymond Boynton discuss killing their stepmother. Carol says that she thinks her stepmother ought to die, and that she must e mad, or she would not be able to torture them the way she does. Both her and Raymond express concern for their sister, Ginevra.
Carol has "chestnut hair", and there is a strong resemblance between her and Raymond They are both "small-boned, well-shaped", and "aristocratic looking". They both also have "slender well-formed hands, the same clean line of jaw, and the same poise of the head on a long, slender neck".
In the lounge at the Solomon Hotel, Dr Gérard observes that Carol is nervous. She makes slight involuntary nervous movements, and her eyes are deeply shadowed underneath, and over bright. Her voice is too quick and breathless. Dr Gérard notes that she is afraid.
Carol later speaks to Sarah King, and tells her that Mrs Boynton was a wardress in a prison, and after her marriage, she had continued being a wardress to her children. Sarah asks Carol to come to her room that night, after the rest of the family have gone to bed.
Carol keeps the appointment with Sarah, and is happy to be able to talk to someone outside her family. However, when she returns to her room, Mrs Boynton is waiting for her, and tells her that she is to have nothing more to do with Sarah. After Mrs Boynton leaves, Carol throws herself on the bed and weeps.
On the afternoon of the murder, Carol goes for a walk with other members of the Boynton family, as well as Mr Cope, Dr Gerard, and Sarah King.
Carol tells Poirot that she returned to the camp at about ten minutes past five, and speaks to her stepmother before returning to her tent. When Poirot tells her that he overheard the conversation she and Raymond had at the Solomon Hotel, she tells him that they were mad that evening, and did not really carry out their plan.
Miss Pierce later tells Poirot that she saw Carol throw a brightly glittering object into the stream. Miss Pierce later picked the object up, and found that it was a hypodermic syringe.
Poirot later explains that when Carol returned to the camp, she found Mrs Boynton dead, and thought that Raymond might have killed her. He suggests that she may then have found a hypodermic syringe in his tent, which confirmed her suspicions, and which she then threw away.
At the end of the novel, Carol marries Jefferson Cope. They, together with other members of the Boynton family, attend a production of Hamlet, in which Ginevra is performing. They then go to the Savoy for supper.
Appointment with Death (1988 film)
In the 1988 film adaption of Appointment with Death, Carol Boynton is portrayed by Valerie Richards. Her role here is fairly similar to that in the original book. She meets Sarah King to send Raymond Boynton's apologies for not being able to meet her (his stepmother had prevented it). She also gives Sarah some background about her unhappy family. Carol's conversation with Raymond about their stepmother needing to die is also depicted, and overheard by Poirot, although this took place on board the ship from Trieste to Jaffa. Unlike the original novel, Carol does not end up with Jefferson Cope at the end.
Appointment with Death (2008 ITV adaptation)
In the 2008 ITV adaption of Appointment with Death, Carol Boynton is portrayed by Emma Cunniffe. Here, because Nadine Boynton is not cast, Carol takes on the role of managing Mrs Boynton's medications. Unlike the original novel, allt he children, including Carol, are adopted rather than stepchildren. Carol's conversation with Raymond about their mother needing to die is also overheard by Poirot. This conversation takes place in an abbreviated form, and nothing much more is made of this later. At the denouement, Raymond and Carol do not confess to having come up with a plan to kill Lady Boynton. Like the 1988 adaptation, Carol does not end up with Jefferson Cope. Here she and Jinny decide to take a holiday on their own to Egypt.