An Unsuitable Job For A Woman (1972) – P. D. James
Young Cordelia Gray finds herself the sole owner of a private detective agency after the suicide of her partner Bernie. Fortunately for the business, wealthy scientist Sr Ronald Callendar soon hires her to investigate the death of his son. Not that there was anything suspicious about it. It's just that Mark Callendar committed suicide, and Sir Ronald wants to know why. Cordelia travels to Cambridge to investigate, and inserts herself into Mark's social circle. After spending time at the cottage where he stayed in…