An episode of Sherlock can pack in a lot, much of it due to the 90-minute runtime and the show's propensity for twists. Of course, the climactic twist of the first episode of season four saw the death of John Watson's wife Mary — a big moment that was brought down by uneven pacing and the fact that her death was more about the relationship between John and Sherlock than Mary herself. Some fans were upset with the series, and with just three episodes per season, there was little room for error heading into episode two, "The Lying Detective."
The good news for Sherlock fans: As a whole, "The Lying Detective" is a strong return to form. Unfortunately, the show's fixation on twists left one too many on the table, with the final reveal before the credits feeling a lot more like a Scooby-Doo villain ripping off his mask than a prestige detective drama leaving viewers on the edge of their seat.
"The Lying Detective" effectively balances a disturbing case while its protagonists grieve Mary's death
While the expectation is that Sherlock and John will ultimately make amends after Mary's death (though John has every right to be upset with him after she was shot), her death would be cheapened even further if Sherlock and John were suddenly on a new case. Director Nick Hurran makes good use of the show's long runtime, taking extra care to show us John's grieving process.
His infant daughter isn't always in his care; he's changing therapists by the week; oh, and he's having conversations with Mary. Much like Elliot Alderson's talks with his dead father in Mr. Robot, this is, very plainly, not a healthy thing for John.
He is also steadfast in his refusal to interact with Sherlock, who's taken Mary's death about as well as you might expect. It's suspected he's using again; Molly's estimation is that he's in the same shape as the corpses she examines at the morgue. But in his psychedelic state he stumbles upon a potentially threatening adversary: a rich entrepreneur, Culverton Smith (played by Toby Jones), who Sherlock boldly proclaims is secretly a serial killer.
At first, it's hard to determine if Sherlock has made a startling discovery, or if he's just audaciously theorizing about an admittedly creepy public figure. John's reluctance to help, coupled with Sherlock's addiction, doesn't make for a clear-cut investigation.
Turns out, however, that's exactly how Sherlock planned it. There was more to the posthumous message Mary left for Sherlock in the season four premiere, after she asked Sherlock to save her husband. She also needed Sherlock to "go to hell" — the only way to convince John to forgive him for her death. What better way to do so than for Sherlock to embrace his drug addiction and go toe-to-toe with a serial killer?
The reveal that Smith was actually a killer isn't a shocker, and it isn't intended to be (but yeah, it's still very creepy than he can walk through secret corridors or a hospital to kill people). It's an elaborate setup to bring the show's protagonists, Sherlock and John, back together in good-ish graces. At least, on good enough terms that Sherlock can go forward. But where the show's heading — based on the final big twist of "The Lying Detective" — is ultimately unsatisfying.
The sibling twist was well-intentioned and compelling, but came off too silly
John makes a return to his therapist at the end of "The Lying Detective," but the therapist lets on too much about John's conversations outside of their sessions. Unconvincing in her backtracking, it's revealed that the mysterious woman has been pulling a few strings in season four.
She is the woman John was sending flirty texts with after a brief meeting on the bus (the source of his guilt after Mary's death), and she's the woman Sherlock had seemingly hallucinated when meeting with Smith's daughter. She wasn't his daughter, but he did meet with someone that night. So who is she?
It's the rumored third Holmes sibling. Eurus Holmes has been revealed — now, presumably, as the big antagonist for the final episode of season four. Eurus as a character is fascinating, but for someone that's intended to instill some fear in the viewer — considering how easily she deceived both Sherlock and John — it's hard to take Eurus too seriously when she's unveiling herself and changing contacts in front of John. Sherlock's intention was a serious, mind-blowing reveal, but instead it's more than a bit campy.
Still, it sets the stage for what should be a gripping end to season four; and perhaps, the culmination of Benedict Cumberbatch's take on the world's most famous detective.