The Sign of Three

It was written by Stephen Thompson, Mark Gatiss and Steven Moffat,[1] and stars Benedict Cumberbatch as Sherlock Holmes and Martin Freeman as Dr John Watson.

When Sherlock and Watson arrived at the Guards' quarters, Bainbridge was found seemingly stabbed to death in a locked shower stall with no weapon in the room.

John's knowledge of human nature lets Sherlock conclude that the perpetrator is a man bored with marriage, who adopts the names of recently deceased single men and uses their unoccupied homes to meet women.

Sherlock deduces that Bainbridge had been stabbed while on duty, with a stiletto-type blade through his belt, which being worn tightly around the waist, prevented him from feeling his injury and also held the flesh together, so damage did not take effect until he removed it.

The Radio Times reported that McCarthy was recruited "following the departure of director Paul McGuigan, who is credited with having set the distinctive visual template for the programme".

[6] According to some sources, such as the Radio Times,[6] "The Sign of Three" was written by Steve Thompson, who had previously authored the Sherlock episodes "The Blind Banker" and "The Reichenbach Fall".

The Independent's Neela Debnath commented, "While it is not the strongest story of the Sherlock saga, the writing is just as sharp and fresh, with the mind palace element toned down a few notches.

"[13] Similarly, Oliver Jia of The Punk Effect stated it as "no doubt the odd duck of the entire Sherlock canon," but proceeded to call the episode "...a clever, hilarious, and moving piece of fine television.

"[14] Former Mayor of London and Prime Minister of the United Kingdom Boris Johnson responded to allusions made to him within the fictional newspaper articles about the "Water Gang" which appeared on screen during the episode's opening moments.

The lower portion of the front page of a mocked-up newspaper described an unnamed London Mayor as "dithering, incoherent, and self-interested", listing "bizarre" policies including a "recently-mocked concept of putting an airport in the middle of the estuary", which The Telegraph say is "a clear reference to Boris Island.

"[15] Johnson suggested that the joke, which The Telegraph reported was "visible for just a matter of second[s]",[15] was "perfectly legitimate" as political satire and also could have been directed at the previous mayor.

"[16] IGN's Daniel Krupa had a more negative review, praising Benedict Cumberbatch's acting and some heartfelt, tender moments, but he was critical of the pacing, stating that "the rhythm was just erratic, never allowing you to really ease into the plot", and criticised the further exploration of the character's lives, rather than the adventures.