The renowned blue ruby was taken in such a sophisticated manner that only one culprit could be blamed – Professor Moriarty. Holmes must retrieve it and, meanwhile, steer a youthful pickpocket toward the right path. In the following episode, Moriarty aims even higher by pilfering a classified submarine from the Navy. What purpose does he have? Holmes once more pursues him in a clandestine operation that threatens national security and its implications.