A wealthy young aristocrat employs "Holmes" to escort himself and his mother on a train from London to Edinburgh alongside the legendary Star of Rhodesia - a diamond the size of a duck egg. Together with trusty sidekick "Dr. Watson" and "Insp. Lestrade" who is ostensibly off fishing for salmon (it isn't quite the season) they embark on a singularly dangerous train journey. It's got plenty of dud trails for our duo, even some appropriated tea pots and a co...