Dr. Thorndyke, medical scientist and barrister, and the first great exponent of forensics in detective fiction, here takes on the case of an unusual and perplexing jewel heist. R. Austin Freeman, well known for his experimental story construction, tries a very radical approach, combining the genres of adventure and detection in a single book. The first half of the novel deals with a major consequence of the robbery: the exploits of the chief suspect who has decamped to West Africa under an assumed name to avoid capture, only in the second half is the robbery fully described, and Dr Thorndyke brought in to apply his formidable mental powers to solving the crime.