The 1857 Divorce Act paved the way for a new career for women: that of the private detective. To divorce, you needed proof of adultery - and men soon realised that women were adept at infiltrating households and befriending wives, learning secrets and finding evidence. Whereas previously, women had been informal snoops within their communities, now they were getting paid for it, toeing a fine line between offering a useful service and betraying members of their sex for money.

Over the course of the next century, women became increasingly confident in gaining work as private detectives, moving from largely unrecognised helpers to the police and to male detectives, to becoming owners of their own detective agencies. In fiction, they were depicted as exciting creatures needing money and work; in fact, they were of varying ages, backgrounds and marital status, seeking adventure and independence as much as money. Former actresses found that detective work utilised their skills at adopting different roles and disguises; former spiritualists were drafted into denounce frauds and stayed to become successful private eyes; and several female detectives became keen supporters of the women's suffrage movement, having seen for themselves how career-minded women faced obstacles in British society.

These were groundbreaking women, working in the shadows, often unnamed in press reports. Even today, they are something of an unknown, yet of intense interest to the public, their work largely an enigma. This new book seeks to shed light on the female detectives who have worked over the past century and a half to uncover wrongdoing and solve crimes.