When her maid Beatrice Taylor became pregnant out of wedlock, Miss Brent dismissed her. The maid later committed suicide. Miss Brent showed no remorse for what she had done since she considered the suicide only Beatrice's fault.
She had been at Bellhaven Guest House for two summers prior to the opening of the story. There, he had met a certain Miss Oliver. Mr Owen used her name to lure Emily to the island along with other nine guests. Her death was caused by a lethal injection of cyanide using Dr Armstrong's syringe after her coffee had been laced with chloral. The murder weapon was eventually found by William Blore.
- 1945 - In the 1945 film, Miss Brent is portrayed by actress Judith Anderson. In this adaptation she is accused of being responsible of the death of her young nephew.
- 1965 - In the film from 1965, the character is renamed Ilona Berg and is portrayed by Daliah Lavi. She is accused of murdering her husband.
- 1974 - In the 1974 adaptation, the character is renamed Ilona Morgan and she is portrayed by actress Stéphane Audran. She is accused of murdering her husband.
- 1989 - In the 1989 film the character is renamed Marion Marshall and is portrayed by Brenda Vaccaro. Mr. Owen accuses her of being responsible for the death of an actress named Beatrice Taylor.
- 2015 - In the 2015 And Then There Were None miniseries, she was portrayed by Miranda Richardson. Her role is mostly faithful to the original one. However, here it is her who finds the body of John Macarthur and not Dr Armstrong. Here, she asked Vera Claythorne to make her some tea before dying, so she is the one who finds her body instead of the whole group.