Iris Henderson is a fictional character from the classic mystery novel "Murder on the Orient Express" by Agatha Christie. She is portrayed as a strong-willed and resourceful woman who becomes involved in the investigation of a murder that takes place on a luxurious train traveling through Europe. In the story, Iris is depicted as intelligent and observant, often assisting the famous detective Hercule Poirot in unraveling the complex web of clues surrounding the crime. Her character adds depth to the narrative, showcasing themes of justice and morality throughout the plot.