The wedding may be over, but for Sherlock fans the after party has just begun! Read our full recap of series 3′s sophomore effort, and discuss the episode with fellow fans! This post contains spoilers.

We open with Lestrade and (a returning) Donovan on an eighteen month long chase to catch a criminal gang – as Greg is about to finally put the cuffs on the network, he gets a series of urgent texts from Sherlock asking for his help, repeatedly. Abandoning his glorifying moment, he rushes to 221B with back-up to discover the super sleuth struggling with “the hardest thing” he’s ever had to do in his life: writing the best man’s speech for John and Mary’s wedding.

“The Sign of Three” was something new for the hit BBC show, and far more a character piece than a crime drama. This was reflected in the opening thirty minutes, as instead of a thrilling murder we are treated to an exploration of Sherlock’s character, and the changing dynamic of his relationship with John and wife Mary.

Post credits, Mrs. Hudson walks in on Sherlock practising his dancing, or at least that’s how it seems. As it turns out, he’s composing the Waltz for the soon-to-be-happy-couple’s first dance. He sits with his landlady, and explains how he doesn’t see the point of marriage, and how it changes nothing. Finally, he “gets ready for battle” – and so does a mysterious figure in military uniform.

At the start of the reception, Sherlock joins the groom in welcoming the guests – and the mysterious figure is revealed as John’s friend and former superior, James Sholto. Sherlock is confused at never having heard of him before, but Mary insists John talks about him “all the time.” The crowds pile in, and the time is finally upon us, as the great detective prepares to start his speech.

Sherlock Benedict Cumberbatch in The Sign of Three

But, just as the speech starts we flashback to Molly approaching Greg and Mrs. Hudson about the frankly terrifying prospect of Sherlock being chosen as best man. We now continue to jump between the speech and wedding preparations – Mike Stanford (the man that brought the Baker Street boys together) gets a cheeky mention in the telegrams, while we see the sheer awkwardness of John requesting that his former flatmate assume the role we now see him in. Cue a long silence, as Sherlock tries to explain all of the things he meant to say (but didn’t). After a rare and out of character moment of sentiment, Holmes decides to remedy the situation by sharing some “funny stories” from John’s blog.

Once we’ve whisked through an assassin dwarf, and a literal elephant in the room, John (under instruction from Mary) takes Sherlock out on a case to try and reassure him that the couple won’t forget about him once they’re wed. And so we meet a scared member of the Queen’s Guard (played by Harry Potter star Alfie Enoch), who has become concerned about a photographer who is paying special attention to him. The duo go to investigate, but before they can find the serviceman his corpse is found in a locked shower with no murder weapon. Sherlock opens the case up to the wedding guests, who make misinformed guesses as to how the guard was killed. However, he reminds the assembled guests (and the audience) that the mystery isn’t important – John, and his caring nature is what everyone’s there for.

Sherlock Benedict Cumberbatch and Martin Freeman in The Sign of Three

And so we reach what is quite possibly the most hilarious run of scenes we’ve ever seen in the show, as Sherlock’s scrupulous efforts to avoid a hangover are marred by John’s equally determined attempt to get trashed. The boys have to come home early after a few too many, and a near miss with a rowdy fellow drinker. As they play a drinking game, the crime solvers are interrupted by a woman who appears to have dated a ghost. They investigate the scene, and after some seriously questionable deductions Sherlock throws up, and the two spend the rest of John’s stag do in a jail cell.

Revived by Mrs. Hudson, the consulting detective turns to online chat rooms to question some of the other women who have dated a dead man. He eventually realizes the “Mayfly man” has been checking newspaper obituaries and using the flats of deceased single men as temporary love nests. The best man’s speech seems to be coming to a close, when we realize that the Queen’s Guard’s stalker is at the wedding, posing as the photographer.

Sherlock Alice Lowe in The Sign of Three

As Lara Pulver’s Irene Adler makes a surprising cameo and John’s middle name becomes an important plot point, Sherlock finally pulls the puzzle together thanks to the help of a Mycroft apparition. The super sleuth shouts “Vatican cameos!”, and John springs to action, instantly knowing that someone is in danger. Mary joins the boys as they hunt down Sholto in his hotel room, wary of an oncoming attacker. Sherlock reveals how the Queen’s guardsman was killed with a dagger in the back of an incredibly tight belt, only actually becoming lethal when the binding is removed. Realizing his death is coming at any time, Sholto tries to remove his belt to end his life, but Sherlock convinces him not to do it on John’s wedding day. As John tries to save his former commander’s life, Sherlock and Lestrade apprehend the photographer, also revealed as the Mayfly Man and exposing him as the Queen’s Guard murderer (his death in fact just being a rehearsal for Sholto’s).

With the mystery solved, it’s finally time for John and Mary’s first dance, accompanied by the beautiful Waltz composed by Sherlock. Sherlock takes “his last vow” (an intriguing bit of foreshadowing for the title of next week’s series finale), promising to protect “all three of them.” And finally, we realise why Sherlock has been acting so odd – as he made one more deduction than he expected to: Mary is pregnant with John’s baby! The guests start to dance, and the best man tries to find the bridesmaid for their customary dance, but she has already found someone else. Sherlock scans the crowd for a partner, but upon realizing that the party has continued without him, leaves.

And so ends one of the strangest episodes of Sherlock we’ve seen for a while. It broke the formula we’ve all grown accustomed to, but also broke new ground as we delve further and deeper into Sherlock’s character than we ever have before.

Next time

All good things must come to an end, and just over a week and half after it began, Sherlock series 3 concludes next Sunday with the heart-stopping finale “His Last Vow,” featuring Lars Mikkelsen’s sinister Charles Augustus Magnussen. Check out the trailer for the episode below!

What did you think of ‘The Sign of Three’?