Spoiler alert: the bottom three episodes in this ranking are all going to be from Series Three.
The Sign of Three
Summary: Sherlock never takes a day off. Not even for his best friend’s wedding. He ends up solving a puzzling attempted murder case during the best man speech at John and Mary’s reception.
Why it’s ranked here: This episode suffers from all the same problems “The Empty Hearse” had. There’s not enough plot, the attempts to humanize Sherlock go overboard until he almost looks like a fuzzy cartoon version of himself, and the mystery features the least plausible murder method this show has seen yet. But I think it still deserves a higher ranking than “The Empty Hearse” for a couple of reasons.
First, though “The Sign of Three” is lacking in plot itself, there’s some subtle foreshadowing that leads up to the much tenser drama of the next episode. The “Redbeard” line hurts quite a bit in hindsight. And did anyone else notice “CAM’s” cameo? And Mary’s reaction to hearing it? I didn’t either until the second viewing. Well played, Moffat. Well played.
Secondly, the drunk scene was freaking hilarious.
And hey, at least this episode HAD a mystery! I did enjoy the courtroom scenes inside Sherlock’s head (and Mycroft’s place in his mind palace could also be interpreted as foreshadowing…). It may not have had a very satisfying solution, but the whole idea of fitting a complex murder mystery into a best man speech was rather clever.