Twists and turns! Betrayals and blackmail! Mayhem and murder and mind palaces! This was a finale episode of "Sherlock" that we won't soon forget, containing one of the most shocking Holmesian moments since Benedict Cumberbatch dropped that bedsheet in the parlor at Buckingham Palace.

From an unspeakable act by Sherlock to a heartbreaking revelation for John, "His Last Vow" gave us much to think, theorize, and salivate over until the premiere of series 4. Here's all the best moments from the episode:

Magnusson Opus
At last we meet Charles Augustus Magnusson: a man who knows everyone's worst secrets, the slimiest extortionist ever to run a newspaper. And when we say "slimy," we don't just mean it figuratively. That scene where he ran his fat, wet tongue down the length of his victim's neck was possibly the most disgusting thing ever to appear on television.

Go To The Mattresses
John Watson might be happily married, but he's also bored, restless, and getting fat. So naturally he jumps at the chance to go knocking at London heroin den and retrieve a neighbor's wayward son. But after locating the boy, and delivering a delightfully self-assured ass kicking to a recalcitrant layabout in the bargain, John makes a surprise discovery: the occupant of the filthy mattress next door? None other than Sherlock Holmes.

Though the detective claims to be working a case, the way Molly slaps him (and slaps him!) when she sees the results of his urine test suggest that he's high on more than the thrill of the chase. But Sherlock's apparent opiate addiction isn't even the most shocking development: that would be the moment when the group returns to Baker Street, and discovers Janine, the bridesmaid from Mary's wedding, emerging from Sherlock's bedroom without any pants on. Unsurprisingly, John's feelings about this mirror our own.

There's Something About Mary
To everyone's great relief, Sherlock's relationship with Janine was only a ruse designed to get him close to Magnusson. But his wasn't the only romance that wasn't quite what it seemed: when Sherlock and John enter Magnusson's office, they find Janine unconscious... And when Sherlock climbs the stairs to the blackmailer's office, he's being held at gunpoint by a black-clad assassin. The assassin? Mary Watson. Mary's move? Putting a bullet in Sherlock's chest.

Behold the Mind Palace
In an episode full of twists, turns, and crafty plotting, we must nevertheless pause to discuss the absolute brilliance that was the scene inside Sherlock's mind palace, as he retreats there for a series of rapid deductions that should ensure he survives the gunshot.

The palace is a maze of memories and hallways, shadows and voices. There are Sherlock's most trusted friends: Mycroft, Molly, and even Philip Anderson. There's the spiraling stairwell from "A Study in Pink." There's an Irish setter named Redbeard and a little boy with a mop of curls. And inside a circular padded room, a chained and straitjacketed Moriarty spits and snarls at the detective that it would be so much more fun and interesting if he just went ahead and died.

A Holmes Family Christmas
Briefly, we get back to the twisty, mysterious matter of Mary Morstan and Charles Magnusson. Mary has revealed the truth: she became Mary Morstan in an attempt escape her past as a CIA agent, and Magnusson knows secrets that would destroy her. A moment of silence for the heartbreaking scene where Mary is demoted from beloved wife to just a client. John forgives her, of course, but still. Ow. My feelings.

But Sherlock is only just recovered from the gunshot that nearly killed him, and it looks like the case has been back-burnered while the Watsons, Mycroft, Sherlock and the elder Holmeses all gather at a very English cottage for Christmas. Or rather, that's what it looks like until it turns out that Sherlock has drugged everyone except for John. There will be no presents or punch this Christmas: they're off to see the wizard.

From Licking to Flicking
Sherlock's brilliant plan — to trade Mycroft's sensitive information-loaded laptop for Magnusson's file on Mary Morstan, and gain access to Magnusson's vaults — has just one big problem: Magnusson doesn't have vaults. He's just got the most amazing, enormous, tricked-out mind palace ever to exist inside a human head.

With the information safely locked away in the villain's brain, Sherlock is out of luck and almost certainly going to be arrested for treason. And Magnusson? He's unstoppable. He can do anything! Particularly, he can flick John Watson in the face, repeatedly, in a display of power that's devastating in its pettiness and seriously uncomfortable to watch. Really, it's no surprise that Sherlock — in a distinctly un-Holmesian moment of lost composure — puts a bullet right between the blackmailer's eyes.

Did You Miss Me? And so, we come to this. Sherlock Holmes: heroin addict, pervert (according to the bogus tabloid story planted by Janine, anyway), traitor, and now, cold-blooded murderer. Our hero came back from the dead only to be dragged through the mud, and not for very long, either: in lieu of prison, Mycroft has arranged for Sherlock to go on a dangerous mission which they both know he cannot survive.

And after another wrenching goodbye between the detective and his doctor, Sherlock boards a plane... Only to be yanked back to London after four minutes when a familiar face makes a sudden appearance on every screen in England.

Did we? Yes. Yes, we did.

"Sherlock" will come back for a fourth season, though it's currently unscheduled.