Hot on the trail of a troupe of diamond and emerald embezzlers comes super sleuth Mr J. G. Reeder, Edgar Wallace's master creation of a detective who confesses to having the mind of a criminal. Reeder's techniques for solving cases are unique, most notably because he was "... a gentleman who liked to work in an office where the ticking of a clock was audible and the turning of a paper produced a gentle disturbance".

The Troupe is Casefile Number 3 which is also included in Casefile Numbers 1,2,3 and 4 from The Mind of Mr J G Reeder by Edgar Wallace.