Beware, s4 spoilers below! and thus links only.
I have created new tags for eps 1-3: Thatchers, TLD, TFP.
If you haven't seen the show yet, stop reading now. I mask spoilers, as always -- and later on, I'll post the setlock I meant to wrap up with. But this is the SPOILER ZONE. Watch your step!
These words from Steven Moffat last Thursday at the #Sherlock BFI screening had us cheering— Sherlockology (@Sherlockology) January 16, 2017
Note that Sherlockology has spoiler-free s4 reviews that may screw up your watching any ep the first time (ep 1 and ep 3, but not ep2) and so I do NOT RECOMMEND that you read those either. Just go watch s4 first.