In the novel Evil Under the Sun, Arlena Stuart-Marshall was an actress. Helen Stuart is her birth name. Arlena was a stage name. She was the second wife of Kenneth Marshall and the stepmother of Linda Marshall. She married Marshall some four years before the events in the book and stopped acting only about a year and a half ago.
She was found dead at Pixie Cove, strangled.
"Her arrival had all the importance of a stage entrance. Moreover, she walked as though she knew it. There was no self-consciousness apparent. It would seem that she was too used to the invariable effect her presence produced. She was tall and slender. She wore a simple backless white bathing dress and every inch of her exposed body was tanned a beautiful even shade of bronze. She was as perfect as a statue. Her hair was a rich flaming auburn curling richly and intimately into her neck. Her face had that slight hardness which is seen when thirty years have come and gone, but the whole effect of her was one of youth - of superb and triumphant vitality. There was a Chinese immobility about her face, and an upward slant of the dark blue eyes. On her head she wore a fantastic Chinese hat of jade-green cardboard. There was that about her which made very other woman on the beach seem faded and insignificant."
Arlena Marshall having a tanned skin is a key detain in the plot of the story.
In the 1982 Evil Under the Sun film (starring Peter Ustinov, Jane Birkin and Nicholas Clay), Arlena was portrayed by Diana Rigg. In this version, she is portrayed as self-absorbed, nasty and disrespectful towards the suspects (excluding Patrick Redfern) and is abusive towards Linda.