Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.
James Moriarty - the greatest criminal mind that the world has ever seen. Sherlock and John knew he wouldn't stay hidden for long. But even they never guessed the sheer scale and audacity of the crime that would propel Moriarty back into the headlines. The crime of the century...........