Sherlock‘s Explosive Season Finale Resets the Series to Status Quo

Benedict Cumberbatch is Sherlock, but undoubtedly Martin Freeman is Sherlock. Though playing an urbane, high-functioning sociopath swishing about in a customized Belstaff Milford coat is what lands you at the top of the marquee, it’s Freeman’s consistently solid presence as John Watson that holds Sherlock together, even when the show is at its most ludicrously convoluted. It’s also the reason why the season got off to a rocky start, having to take time to repair the manufactured rift between Sherlock and John that arose after the death of Mary.

And thank goodness, because Sherlock’s sociopathy isn’t so high-functioning without the influence of John. And though John wound up at gunpoint in the final seconds of last week’s episode, “The Final Problem” reveals it was merely a tranquilizer. Sherlock and John are truly back in action together, this time to solve the mystery of the third Holmes sibling, Eurus (Sian Brooke).

We open on a commercial airliner full of unconscious passengers and flight crew, save for a very scared little girl. When the girl answers a ringing cell phone at the front of the plane, she hears Moriarty’s voice come out the other end, promising “one final problem.” But first, in order to confirm the existence of the sister he cannot remember, Sherlock and John stage a strange nightmarish vision for Mycroft, involving being chased by sword-wielding clowns and an actress dressed as a little girl skulking in the shadows. When asked why Sherlock would take such ridiculous means to get Mycroft to confess, John admits it was his idea: Mycroft would only spill the beans if he was pants-wettingly terrified.

Mycroft seeks out the duo at the Baker Street apartment the next day, and finally explains the strange case of Eurus, the middle child with an intellect that surpasses even Mycroft and Sherlock’s “deduction thing,” as John puts it. Young Eurus’ sociopathy also surpassed that of her siblings, and in a fit of jealousy she killed Sherlock’s dog, Redbeard, and burned down the Holmes’ childhood home. As a result, Eurus is taken away and imprisoned in a high-security facility on a remote island called Sherrinford (an in-joke, as this was the name of a proposed third Holmes sibling in Sir Arthur Conan Doyle’s unpublished notes).

In an absurd sequence, the meeting in 221B is then interrupted by a motion-sensor grenade sitting atop a Eurus-controlled drone, destroying the apartment and requiring Sherlock and John to jump out their second-story window. It’s an image great for making episode trailers, but laughable in the context of the show. Why would Eurus try to kill Sherlock when clearly she has other plans for him, as we’ll see later in the episode?

Having survived the drone grenade and window jump miraculously without injury, Sherlock, John and Mycroft go to Sherrinford to determine how Eurus has seemingly been able to come and go from her prison cell at will. After a bit of subterfuge involving stolen guard uniforms, Sherlock and Eurus come face-to-face once more after their first meeting in “The Lying Detective,” when Eurus visited 221B Baker Street in disguise. She’s confined to a Hannibal Lecter-style plastic cell, a reference hammered home by a guard warning that the rules for being in the same room with her are literally like those in Silence of the Lambs: Keep your distance, et cetera.

Meanwhile, John and Mycroft are confronting the governor of Sherrinford over Eurus’ ability to escape. It turns out that Eurus’ true brilliance is her ability to essentially “reprogram” anyone she speaks to, planting suggestions in their minds—including that of the governor. The plastic walls of Eurus’ cell are merely an illusion, and she thus has full reign of the facility.

Sherlock, John, Mycroft and the governor are all rendered unconscious, reawakening in a locked room. Eurus appears to them on a video screen, intent on putting them through a series of sadistic, Saw-like games, with Eurus as Jigsaw and aided by pre-recorded video of a taunting Moriarty—who had visited Eurus five years prior, at her request. It was she all along who was the mastermind behind the Moriarty “Miss Me?” messages. (And what a joy it is to see Andrew Scott back briefly as Jim Moriarty, slithering into the flashback like a flamboyant lizard to the tune of Queen’s “I Want To Break Free.”)

Eurus stages a series of life-or-death puzzles for her brother, including the case of the girl on the plane, with whom Sherlock is now able to talk to through the cell phone the girl picked up at the beginning of the episode. Each game comes with a sick twist: In order to advance through the puzzles and save the girl, first Sherlock is given a gun and must choose who will shoot the governor, John or Mycroft. Another game finds him having to cruelly call Molly Hooper and convince her to say “I love you” without being able to tell her that her life is in danger. It’s a genuinely terrifying sequence, nearly as good as Moriarty’s death-defying games in “The Reichenbach Fall.”

At each step, Eurus needles Sherlock, randomly doling out punishment or introducing new complications into the game. When he finally loses it, it’s John who snaps him out of it: “Today, we are soldiers.” It’s eventually revealed that Redbeard was not, in fact, Sherlock’s dog, but his childhood friend, whom Eurus pushed into a well to drown. The well drowning is also Sherlock’s final problem, as Eurus condemns John to the same fate unless Sherlock can solve the mystery of the girl on the plane. Which was all a ruse, as Sherlock deduces: The girl on the other end of the line was Eurus all along, and the plane was essentially her version of a mind palace—a mental space in which she is above everyone (literally) yet totally out of control.

With John saved and Eurus safely re-ensconced in Sherrinford (for real this time), “The Final Problem” resets the series to the original status quo. They clean up the wreckage of the bombed-out apartment, and pick up where they left off in the days before Mary and before Sherlock’s faked death: together again, taking on cases-of-the-week at 221B Baker Street.

Mallory Andrews is a senior editor for cléo, an online journal of film and feminism. She is a bi-weekly columnist for Movie Mezzanine, and has also contributed to The Dissolve, Indiewire, Cinema Scope and Esquire.