*WARNING: SPOILERS FOR SHERLOCK SEASON FOUR FINALE*

Sherlock's obsession with pulling the rug from underneath its fans is inevitably going to leave a few disappointed on each occasion.

But to some, the BBC series crossed something of a line in the finale to season 4; with the revelation that Sherlock and Mycroft's sister Eurus was, in fact, something of a psychotic genius - leading the latter to lock her away in a top-secret prison for the criminally insane, while wiping Sherlock's memory of her existence.

What follows is Sherlock and Mycroft's involuntary participation in Eurus' ruthless mind games; torturing the pair with videotaped threats from a still-dead Moriarty, and forcing Sherlock to solve elaborate murders before killing all its suspects anyway.

Things ended with the revelation that Eurus wasn't responsible for the death of Sherlock's dog Redbeard, but for his childhood best friend Trevor; though Sherlock, of course, soon managed to save the day and lock Eurus back behind bars before it was too late. Though the episode turned out to be a little too much for some viewers.



Plenty of fans, however, did find emotional closure with the episode; especially considering Benedict Cumberbatch and Martin Freeman may never again return for another round as Holmes and Watson.