Anna Katharine Green (1846-1935) was a pioneering figure in the American detective fiction genre, often credited as the mother of the detective novel in the United States. Her literary career began with the publication of 'The Leavenworth Case' (1878), a novel which garnered attention for its intricate plot and the use of a detective's perspective—a groundbreaking approach at the time. Green's writings often featured strong female characters and meticulously constructed mysteries, a style that would greatly influence later writers, including Agatha Christie. 'XYZ: A Detective Story' is one of her lesser-known works, yet it encapsulates the qualities that define Green's oeuvre: attention to detail, a penchant for suspense, and the ability to keep readers engaged until the very end. Her body of work comprises more than 40 novels and numerous short stories. Green's prose is distinguished by its Victorian flair and the incorporation of legal and procedural accuracy, which stemmed from her extensive research and her father's background as a lawyer. Though her popularity waned with the advent of hard-boiled detective fiction, her contributions to the genre's formative years continue to be recognized by scholars and enthusiasts of crime and mystery literature.