He has in the past assisted Scotland Yard, quite unofficially, in several investigations (and with considerable success). Now Scotland Yard is facing a new challenge. A series of daring jewel robberies in the Midlands have created a sensation in the popular press. There are those at the Yard who suspect that these are no ordinary crimes - that there is a criminal mastermind behind them. A couple of minor members of the gang have met with sudden and very fatal accidents. It seems that if there is a large criminal organisation behind the robberies they are quite prepared to resort to murder to keep their secrets.