Blackmailer McDonald is murdered by one of his victims. His body is dumped in the trunk of his enemy, newspaper editor Kruger and the plot begins.
Holmes and Watson meet Inspector Lestrade on a train to Scotland, in which Lady Margaret Carstairs, the owner of a famous diamond, the Star of Rhodesia, and her son Roland are travelling. The owner has asked Holmes to guard the huge diamond, but soon Roland is murdered and the diamond stolen. Holmes must find the diamond and uncover the murderer, both of whom must still be on the train.
Based on the Sir Authur Conan Doyle story “The Dancing Men”, Sherlock Holmes and Dr. Watson are placed in WWII europe to help protect a scientist and his invention from the Nazis.
A convicted thief in Dartmoor prison hides the location of the stolen Bank of England printing plates inside three music boxes.