In Agatha Christie's most twisted tale, a spy-turned-private-detective is lured by his former lover to catch her grandfather's murderer before Scotland Yard exposes dark family secrets.

A human story of jealousy, blackmail, self-made men, frustrated ambitions and secrecy that takes place in Melbourne, Australia in the 19th century and involves an investigation into a homicide where the deceased was discovered on the inside of a hansom cab. The influential and secretive Frettlby family is at the center of the mystery, and the name of the killer himself is not as much significance in the story, as is the role of the Frettlby family...