There is a new criminal mastermind at large (Professor Moriarty) and not only is he Holmes’ intellectual equal, but his capacity for evil and lack of conscience may give him an advantage over the detective.

When a chance encounter brings soldier John Watson into Sherlock's life, it's apparent the two men couldn't be more different, but Sherlock's intellect coupled with John's pragmatism soon forges an unbreakable alliance as they investigate a series of baffling cases together.