South London, 1893
Encouraged by a mischievous uncle, and self-taught with American text books, Jane Dowling embarks on an unusual career for a vicar's daughter. She is convinced that she had what it takes to become a private detective and she marches into the seedy offices of Joe Burton and offers her services to join his struggling company.
Jane Dowling's first case is to discover why the body of a print factory manager was found below a railway viaduct. She discovers the man's complicated double life and second family, but then realises she is on the fringes of a major conspiracy and finds herself in danger. Her curiosity and inexperience will put others in danger, and she is locked in a lunatic asylum by a local slum landlord, whose criminal activities she is threatening. Finally, the scale of the conspiracy becomes clear and she must expose those in authority who are perpetuating it, with casualties to friends and foe alike.