... which provides you with the perfect opportunity to rewatch season three and see if you can spot any hints that (you know who) isn't exactly who (you know who) seems. And for you Sherlock fans who are SUPER obsessed, Netflix will also feature Sherlock Uncovered (three half-hour making-of specials) and Unlocking Sherlock (a one-hour behind the scenes documentary on the series). Here's a clip from Sherlock Uncovered in which executive producers Steven Moffat and Mark Gatiss discuss how they came to cast Benedict Cumberbatch and Martin Freeman, courtesy of our good friends at Vulture: