We learn so many dark secrets about Mary on “Sherlock,” and nothing will ever be the same

The game is afoot once again, and that means that there are spoilers for Sherlock Season 4 out there, including right here! So if you haven’t yet watched “The Six Thatchers,” stop what you’re doing and go ahead and boot up BBC, or PBS, depending on where you are in the world.

After what has felt like an eternity, Sherlock is finally back, and he is worth the wait. The action picks up shortly after the end of Season 3, and the one-off Christmas special, “The Abominable Bride.” Within 20 seconds, Sherlock is off the hook for Charles Augustus Magnussen’s murder, and that’s good. Because now someone is trying to kill Mary.

As we learned over the course of Season 3, Mary is a retired “agent,” which is just the nicer word for assassin. She was part of a deep-cover group, code name A.G.R.A. When Mary told John that A.G.R.A was her name, she was sort of telling the truth. It’s actually an acronym for the first letters of this four-person group: Alex, Gabriel, A.J. and…Rosamund. Which, surprise, is exactly what John and Mary name their newborn daughter (Rosie, for short).

Six years ago, Mary (or, Rosamund) and her team were tasked to go in and free some hostages, but it quickly turns into a suicide squad situation. Everything goes south, because someone tipped the terrorists off that A.G.R.A was coming in. While Mary escaped, no one else did. Alex was captured and killed, A.J. was captured and tortured…and actually there’s no word on Gabriel so remember him for later, he might come back, you never know.

BUT, getting back to Mary, A.J. is pretty PO’ed to learn that she basically left him to die all those years ago, and now he’s determined to kill her. He’s on an odd rampage across London, smashing Margaret Thatcher statues, trying to find his own USB drive to basically take Mary down.

It does not work, because Mary is super-smart and badass, and she’s also got Sherlock and John on her side. A.J. is killed, but that still leaves the bigger question: WHO was responsible for this mission going south all those years ago?

In true Sherlock fashion, it is a roundabout way of getting there, and surprise, it was Lady Smallwood’s secretary, Vivian, all along! I mean, of course. Duh.

And, in true Sherlock fashion, things are never actually that easy. Vivian, not wanting to go easy, SHOOTS SHERLOCK.


This is where everything starts going south in the episode. John arrives on the scene moments later, but it is too late. Mary dies in his arms, and it is so heartbreaking, especially because John immediately blames Sherlock, indirectly, for her murder. This was not supposed to happen.

However, even in death, Mary’s still got secrets and sends Sherlock one last message. She’s got a new case for him: Saving John Watson. Buckle in, because this is going to be a very bumpy Sherlock season.