Darkness clung to the early Baker Street morning as Dr Watson opened the front door. The night watchman held out a small slither of paper. Written faintly upon this were just two short words: "Help me."

Sherlock Holmes must use all of his remarkable powers of deduction to identify the author of this desperate plea. His investigations lead him and his companion into a murky conspiracy - a sinister secret society plotting a fiendish scheme that could destroy the British economy and bring down the government.

From a thunderous carriage chase through the streets of London to a deadly shootout on a remote island off the North-East coast of England, can Holmes and Watson uncover the dark secret that lies within the sinister 'Ex Tenebris' club?