In the dark days of World War I, an aristocrat’s suspicious suicide propels the female detectives of Mayfair 100 into a sordid world of blackmail, betrayal, and tragic secrets

When the phone rings at the Mayfair 100 exchange, the news is rarely good, and this time is no exception. The Duchess of Penhere’s daughter, notorious society gossip queen Lady Adeline Treborne, has been found dead in her room in what appears to be a suicide—but her family suspects foul play.

The secret Mayfair team of amateur female detectives has been restlessly awaiting their next case, and this will prove one of their thorniest. When Dr. Caroline Allardyce performs an autopsy, she is able to conclusively prove that the woman was murdered. Lady Treborne had made many enemies through her vicious gossip column, so there's no shortage of suspects.

Supported by a cadre of professional police officers, the Mayfair women launch their investigation, but there’s much more to this case than meets the eye. As they venture into a world that lays bare London high life at its lowest, the team soon begins to comprehend the danger at hand—and how this tangled web of treachery could ensnare anyone who gets too close.