Ginevra is about nineteen years old, and has golden-red hair. Her skin has "the exquisite clearness that often goes with red hair". She is "over thin", but has a beautiful face. Her voice has a "sweet singing quality that lends enchantment to the most commonplace utterances".
When Dr Théodore Gérard sees Ginevra, he is struck by her smile, he is reminded of "the strange unearthly smile that lifts the lips of the Maidens in the Acropolis at Athens--something remote and lovely and a little inhuman". However, he is shocked to notice that as she sits with her family, her hands are busily tearing a delicate handkerchief into shreds.
According to her sister, Carol Boynton, Ginevra had always been delicate, and Mrs Boynton fussed about her, which made her worse. Carol mentions to Sarah King that Ginevra has been "very queer", and does not always know what she is doing.
Ginevra tells Dr Gerard that she is not really a Boynton, and that she is royal, and the heiress to a throne. She says that there are enemies all around her, and that they try to poison her. She asks Dr Gerard to help her get away.
Dr Gerard later tells Poirot and Colonel Carbury that Ginevra is mentally in an "extremely dangerous condition". He explains that she has begun to display symptoms of schizophrenia. She is unable to bear the suppression of her life, and so escapes into a realm of fantasy. She experiences advanced delusions of persecution, which he says is dangerous, because it is the beginning of what is often homicidal mania, where the sufferer kills in order not to be killed themselves, not for the lust of killing.
When Ginevra meets Poirot, she asks if he has come to protect her, and tells him that she is in danger. She also says that Dr Gerard is in love with her, as she has heard him saying her name in his sleep.
Ginevra tells Poirot that Mrs Boynton was not her mother, but her enemies had paid her to say that she was, and to see that Ginevra did not escape. She also mentions someone in disguise, who looked into her tent on the day of Mrs Boynton's death. Ginevra says that the Sheikh sent this person, because he wanted to kidnap her. When Poirot suggests that these things are not true, Ginevra becomes angry. Dr Gerard takes this as a good sign, as it shows that she knows that the stories she tells are not true. He plans to treat her at one of his clinics in Paris, and then to let her train as an actress.
It is later revealed that the murderer had dressed up like one of the Arab servants on the day of Mrs Boynton's death. The murderer had been going to Dr Gerard's tent, but had looked into Ginevra's by mistake. This was what prompted Ginevra's story of a sheikh in disguise.
At the end of the novel, Ginevra appears in a production of Hamlet, in a London theatre, where she plays the part of Ophelia. It is implied that she and Dr Gerard are in a relationship, as she calls him by his first name, and he calls her chérie. However, it is not stated whether they are married or not.
In the 1988 film adaption of Appointment with Death, Ginevra Boynton is portrayed by Amber Bezer. Here her portrayal is slightly different from that in the original. She is seen as a fairly balanced young girl who likes to dance and have her photo taken at scenic spots. She, like the other Boynton children, believe there was a second will. She told them that her father had told her she would get $200,000 all to herself. Like in the original, Ginevra also experienced the same treatment from her mother. Mrs Boynton prevented her from dancing after dinner on the ship and sent her off to bed early. At Qumran, Mrs Boynton wanted everyone to go off on an excursion but sent Ginevra to take an afternoon nap. It was during this time that Ginevra reported that "a sheikh" dressed in traditional Bedouin robes entered her tent (something similar happened in the original novel). This would later help Poirot in solving the mystery of Mrs Boynton's murder.
Appointment with Death (2008 ITV adaptation)
In the 2008 ITV adaption of Appointment with Death, the character is simply called Jinny and is portrayed by Zoe Boyle. Here her backstory is substantially changed. Like the other Boynton children, she is an adopted child of Lady Boynton.
During the denouement, Dame Celia Westholme admitted that she was Jinny's mother. She was father by Lady Boynton's houseguest Dr Gerard while Celia was working there as a maid. Subsequently Jinny was given over to Lady Boynton for adoption while Celia went off to a convent in Ireland.
Jinny's characterisation is also different from that in the original novel. Although she had been mistreated--there are flashbacks of Nanny Taylor dunking her into bathwater as punishment--she is not as neurotic or unbalanced as in the original. Jinny plays a major role in one sideplot. Here, a gang of slavers planned to kidnap her from her tent. But Jinny fought off and injured her kidnapper by hitting out with a rock. This kidnapper turned out to be Sister Agnieszka.
At the end of the show, Jinny tells Poirot that she intends to assert her independence by taking a holiday with Carol to Egypt on their own,