Ida Arnold is a fictional character from the novel "Brighton Rock," written by Graham Greene in 1938. She is portrayed as a strong-willed and compassionate woman who becomes involved in the life of the young gangster, Pinkie Brown. Her character serves as a moral counterpoint to Pinkie's ruthless nature. Throughout the story, Ida is determined to uncover the truth behind a murder that Pinkie has committed. Her relentless pursuit of justice highlights themes of morality and redemption, making her a significant figure in the narrative. Ida's character embodies the struggle between good and evil in a complex world.