"Into the Forest I Go" was an hour that brought a lot of pieces together in this uneven first season of Discovery, and it ended with a final twist that we now see serves as a sharp left turn into a new arc set in Trek's Mirror Universe. The MU was of course famously established in TOS's "Mirror, Mirror," before lying dormant for decades until DS9 picked up the mantle for its annual hijinks. Then in its final season, Enterprise also ventured into the arena with "In a Mirror, Darkly," which featured some time-bending that brought the USS Defiant back from the TOS era into the Enterprise's prequel era. The events surrounding the Defiant are specifically referenced in "Despite Yourself," which is a solid outing that sets up this new setting and looks to be just the beginning.
What isn't clear is how long we'll be in the MU — and whether this will prove to be a significant story point that has larger implications to this series' characters and reality, or if this is just a detour-like lark for some antihero intrigue. Will this venture into the MU figure into a cohesive or thematic whole for the season, or will we get to the end of it and wonder, "What was all that about?" "Into the Forest I Go" indicated the war with the Klingons was a necessary piece of business that must be dealt with, but alleged it was just the prologue before a more Trekkian scientific mission of discovery could commence. "Despite Yourself," on the other hand, shows signs of this series becoming a series of prologues followed (or interrupted) by more prologues.
At the same time, there's potential here related to the concept of self-identity and the appearance of one to others, a theme that has been present throughout this season especially with regard to characters like Burnham, Tyler, and Lorca. Different roles in the MU may further press these already-present issues. Those issues are on full display in "Despite Yourself," which might be the most thematically cohesive episode of the series so far.
The amusing paradox of the MU is that, for all its darkness and its population of homicidal maniacs, it engenders a lighter tone than the straight-on seriousness of Discovery's normal universe. That's because the MU (with the possible exception of DS9's "Crossover," I suppose) has always been elevated into the realm of comic-book exaggeration. Discovery appears to be following suit, and that allows some of the fun to emerge. (The characters at one point theorize that the Discovery has swapped universes with its evil counterpart, raising the question of what that ship is doing in our universe while this ship is in theirs.)
Perhaps the most inspired choice here is the revelation that the mirror-Discovery's captain is Tilly (nicknamed "Captain Killy" — subtle). This means our awkward and verbally unprepared Tilly must take on the role of pretend-captain while in this universe. In the process, she must undergo a complete transformation of appearance and personality. She must become a different version of herself where she literally lets her hair down. This results in some funny scenes that show promise for letting the character out to breathe a little more. (Also funny: Lorca's "chief engineer" impression using a Scottish accent.)
Meanwhile, Burnham learns that her counterpart, who was formerly the captain of the mirror-Shenzhou, has been presumed killed in this universe by mirror-Lorca. So a plan is enacted for her to alter the "presumed dead" storyline by resurfacing — and bringing Lorca back to the Shenzhou as her prisoner and reclaiming command of her ship. There's a scene where she's attacked by the now-captain of the Shenzhou that took over command after Burnham was out of the picture. This guy has no intention of turning command back over to his former boss, so he tries to murder her instead. This leads to an effective fight scene in a turbolift, and as Michael stabs her attacker she has a look of horror that reveals the distance between her real identity and her assumed one. Role playing here is going to take a toll on the conscience.
As for Lorca — well, there's still the question of how he fits into all this. I remain suspicious over the fact he survived the destruction of his previous ship, the Buran, and I'm even more suspicious about the fact the MU's Buran was also destroyed. There was also that blink-and-you'll-miss-it moment in "Into the Forest I Go" where he apparently overrode the destination of the final jump that ultimately brought the Discovery here. If he brought the ship here intentionally, why? I don't know how this fits into his agenda, given how sideways the whole situation goes, with him ultimately being thrown into an Agony Booth. As always, Lorca always acts like he's on the up-and-up, but there are clues indicating lies and hidden motivations.
Meanwhile, Stamets reveals brief flashes of temporary lucidity in between long bouts of spouting random-seeming oracle-like psychic gibberish containing occasionally ominous clues. As identity crises go, the one existing in between human and oracle is perhaps the most dire.
Correction: The other identity crisis here, and by far the most intense, is Tyler's, as he continues to remember unspeakable surgical horrors undertaken by L'Rell. He visits her in the brig and she tells him what was done to him was a joint effort he willingly participated in, all but explicitly confirming he was transformed from Voq with radical surgeries and brainwashing. She even seems to try "waking" him with an activation phrase that triggers the buried persona inside him. Interestingly, this doesn't completely work, and L'Rell is surprised to discover Tyler still remains partially in control of Voq's mind. We have a programmed personality battling for control against the suppressed personality without knowing for certain what actually lies beneath. (As I've said before, he's basically Boomer on Battlestar Galactica.) Tyler's reaction to this is, understandably, panic. He swears Burnham to secrecy about his disturbing flashbacks because he doesn't want to be sidelined.
So he goes to sickbay to make sure he isn't a ticking time bomb. Turns out he is. Culber finds evidence of massive surgeries, organ transplants, and other possible radically invasive procedures and brainwashing. These apparently slid under the radar during previous exams, explained away by his torture, before Tyler hangs a red flag on them here. That's a pretty convenient conceit considering red flags should've already been hung all over a missing POW who had been sitting for months in a Klingon prison cell. Culber tells Tyler he's grounded until he can get to the bottom of it — and in response Tyler snaps Culber's neck and kills him. Just like that.
It's a rather shocking and sudden fate for a character who was just becoming an interesting part of the ensemble. But I suppose that's the cost/benefit equation when it comes to narrative character deaths: If you must kill a character, doing it in a way that registers as a loss for the audience while also making it a notable moment for the killer makes dramatic sense. Still, that Culber would so foolishly confront a security risk alone in this manner, and the fact that sickbay is so conveniently empty for this to happen (Discovery's general sense of under-population is an ongoing problem) smacks of contrivance — as does the drawn-out serialized plot structure that allows Tyler to go on the away mission with Burnham to the Shenzhou (where they subsequently slide into bed) while Culber apparently lies dead on the floor waiting until next week's episode to be discovered. Is this a Federation starship or a secluded murder-mystery mansion on the upstate coast?
Jonathan Frakes returns to the franchise to direct this episode and it's a mostly effective and entertaining one. Like "Into the Forest I Go," it shows this series working with a more confident narrative that spreads the story around the ensemble pretty well. It looks like we're going to be in the MU for a while. Let's see what the crew can do over here.