In the short story Death on the Nile Lady Ariadne Grayle was the wife of Sir George Grayle. She was independently wealthy and supported her husband who was an impoverished baronet. Over the course of their marriage of some ten years, she had paid off his debts, maintained the household and also supported his niece Pamela.
However Lady Ariadne suffered from "too much leisure and too much money" and this, in the opinion of her nurse Elsie MacNaughton, often produced a pathological condition. She was bad-tempered, ever complaining and a hypochondriac. When she embarked on a Nile criuse with her family, most of them believed her complaints of ill-health were fake or imagined. However she subsequently died from strychnine poisoning on board. What happened and how Parker Pyne solved the mystery forms the main plot of the story.
Lady Ariadne is described as "a big woman, not bad-looking as regarded features, but her face was fretful and lined, and the lavish make-up-she applied only accentuated the blemishes of time and temper. Her hair had been in turn platinum-blonde and henna-red, and was looking tired in consequence. She was overdressed and wore too much jewellery."