Master sleuth

What an explosive coup Sherlock pulled off last night - constant but well-paced surprises: Mary Morstan being a secret assassin seeking to leave behind her past life; Holmes' real name of William Sherlock Scott Holmes (I've never read the books); the return of Moriarty (yes, we did miss you); and, perhaps most shocking of all, Mycroft Holmes telling his brother that should Sherlock die it would break Mycroft's heart.  Killing Rupert Murdoch was the cherry on top.
It really built up the Murdoch-alike of Arnold Magnussen as mentally brilliant and equally devastating as a velociraptor.  Like the Devil, he is full of lies - saying he is not a murderer, just a businessman, on the very day that one of his blackmailed victims commits suicide. His mind palace is arguably more capacious than Sherlock's but as in despotisms, an empire can crumble after the death of its founder if everything rests on him.  Muroch of late has been a figure of fun, Steven Moffat restores to him his chilling reputation (as well as Moffat cheekily implying that look how brave he is by writing such a vicious portrayal).
The brilliant final twist of Moriarty coming back from the dead stops those Sherlock conspiracy forums being mothballed and the die-hard fans can speculate about how Moriarty survived a bullet to the head through the mouth (was what we saw a body-double or was what we saw the version told to John Watson by Sherlock, who then chronicled the latter on the former's blog; the possibilities will be endless).  There was the little teaser of Moriarty being inside a padded cell within Sherlock's mind palace - defeating him again might need recourse to this facet.  I hope it is only twelve months before we get a return as 24 months to get another fix would be beyond even Sherlock's fortitude, even if he was being a crack addict 'only' for a case.