Now that we've gotten past the detour that was Empress Philippa Georgiou, Discovery is on track towards its endgame. It does so by refocusing on the central mystery of the season: the cause of the Burn.
We pick up at the end of Georgiou's memorial service. Adira is standing by Stamets, awkward and unsure of themself since they still don't feel they're fitting into Discovery's established social circles, when Gray suddenly makes his reappearance. Even though Stamets can't see him, he believes Adira when they say Gray is there, and tells Gray firmly that "if this wasn't a memorial service, I would give you a piece of my mind." Adira and Gray then have a short conversation where Gray apologizes and Adira admits their hurt, but says they can figure things out. They are interrupted by the ship's computer signaling that it's finally found more data on the Khi'eth, and in fact there is a life sign in that crashed, 125-year-old ship. Tilly objects, saying it couldn't be Dr. Issa after all this time and radiation exposure, and Saru says, no, it isn't. The red marks on Dr. Issa's forehead that everyone had previously taken for radiation burns was a sign that she was pregnant, and the life sign detected must be her child.
Discovery jumps into the Verubin Nebula to rescue the child, only to be battered and whipped about by ionizing radiation. They can't stay there, but Booker volunteers to take his little matter-morphing ship inside and see if he can get coordinates. He does so and also finds a stable "pocket" where Discovery can jump back in (though it can't stay there for very long), but in the process both he (and Grudge) get a high radiation dose and the autopilot has to bring him back out. He discovers that the Khi'eth has crashed into a "massive dilithium supply," and indeed, the entire planet is laced with dilithium.
Saru briefs Admiral Vance, who notes this development has heightened the urgency of their mission: in addition to rescuing the survivor, they have to stake the Federation's claim to this planet. Saru also reveals he intends to accompany the away team to recover the Kelpien, leaving Tilly in charge. Vance notes he had to send half the depleted Federation fleet to Kaminar, Saru's home planet, because the Emerald Chain was holding more fake "training exercises" there. Everyone makes note of the fact that Osyraa is trying to draw Discovery out, and Tilly even says that "she wants our spore drive," but somehow this momentous tidbit isn't given the seriousness it deserves? (Something which will come back to bite them big time.)
Saru, Michael and Culber constitute the away team, which leads to a scene of Stamets loudly objecting and Culber stating that he "needs to do this for me." He needs a sense of purpose that has been lacking since Discovery's jump to the future, and he can relate to the Kelpien survivor being alone for decades. At this, Stamets subsides, and the two kiss before Culber leaves. (Adira is watching this in the background, which is obviously the setup for what they later do.) After Michael meets Booker (and Grudge) in sickbay, and confirms that they are recovered--freshly reconstituted DNA and all--from their little jaunt (and one thing I thought was funny as the scene progressed was that the cat playing Grudge was starting to squirm insistently in Booker's arms, demanding to be let down; I imagine they'd had too many takes), she tells Book she intends to accompany Saru, because he might not be thinking clearly under the circumstances. (Which is rich coming from Michael Burnham, with her established history of impulsiveness and unclear thinking, but well....) Before they leave, Michael also talks to Tilly, trying to boost her confidence before the latter takes the big chair, and tells her about a little hidden burr under the left arm of the captain's chair, available for nervous stroking in a pinch.
Discovery jumps back into the stable pocket with Culber giving fairly alarming instructions: they have radiation meds and badges, but they can only stay four hours. Saru hands the conn off to Tilly, and the three beam into the crashed ship.
But they arrive in a vastly different condition from how they left. Culber is Bajoran, Michael is a Trill, and Saru is Human (and thus we get to see Doug Jones free of his six inches of prosthetics and his high-heeled boots). They're in an "advanced holoprogram," and unfortunately, not only is their appearance changed, but all their equipment, including the radiation meds, is being hidden from them. They stride off through the background of snowy forest, and come upon a weird, gloomy open space with lots of stairs up and down and strange finny things swimming in the background. (The CGI and other effects in this episode is really good.) Descending the stairs to the lower level, they see first a locked chained door and then the Kelpien survivor. Saru tries to talk to him about the "outside." He obviously has no notion of what that means, and grows frightened and runs off. At the same time, whatever's behind the door starts pounding and howling. Burnham says they're basically dealing with a child, and Culber urges Saru to treat this like a first contact. Burnham tells Saru and Culber to go after the survivor, and she will hold off whatever is behind the door.
What's behind the door proves to be a very cool CGI monster, with a mixture of a Kelpien body draped in kelp fronds and even a hint of Cthulhu. It chases Burnham up and down the creepy multidirectional stairs, and eventually she falls over the edge. But she doesn't fall down, instead falling up--to a higher level where the survivor is waiting. Thinking fast, she pretends to be another program devoted to teaching "the dynamics of social interaction" and tries to draw him out.
Meanwhile, Saru and Culber go into another room where a Kelpien Elder is sitting in a chair. (There's a lot about Kelpien culture in this episode, which is another reason Saru is so distracted.) Saru sees drawings on the walls telling of the survivor's name: Su'Kal, or "beloved gift," the name given to the first child born after a tragedy, symbolizing the end of suffering. Saru then talks to the holographic elder, who reveals that this entire program was made by Dr. Issa before she died, to raise and guide her child. (Although I would really like to know how it produced food and water for 125 years.) The Elder tells them Su'Kal runs to the "fortress" when he is frightened, and Culber goes in search of it. Saru looks at the book the elder is holding, and sees a clue inside. Su'Kal is shown protecting himself from the monster, which is the fear he will not face. Saru hurries to catch up with Culber, and the two of them cross a yawning, wind-whipped seascape to the fortress, where Michael lets them in.
Inside, Su'Kal is building the same cairns depicted in the book, to ward off the monster. The black kelp-draped beast comes down the stairs and attacks Su'Kal, and in his terror he screams and sends out an energy surge. Saru approaches him and starts singing to him in the Kelpien language, and that succeeds in calming Su'Kal down.
While all this is going on, Tilly is undergoing an unfortunate, and brutal, baptism by fire, one she is not at all ready for (although I don't think she does all that badly, up to a point). While they're sitting outside the nebula, waiting for the shields to be repaired so they can jump back in, long-range sensors indicate another ship is approaching, and it's coming in fast. Tilly, trying to figure out who this is, ends up talking too long and getting taken by surprise--because it's Osyraa's warship, the Viridian. (Remember how everybody was so unconcerned that Osyraa was trying to draw Discovery out?) Tilly orders the Discovery to cloak (apparently a cloaking mechanism was also part of their refit, along with the ubiquitous blue nanotech goo). Osyraa hails them, and she and Tilly trade barbs for a bit. But Discovery's shields are still not fixed, and they're kind of stuck until they are. Tilly tries to stall until they can jump back into the nebula, and this may have worked--except for the energy wave projected by Su'Kal outward from the planet, which washes over Discovery, threatening to destabilize its dilithium and warp core, and decloaking both ships.
(So....Su'Kal caused the Burn? This is not unprecedented, I suppose, considering Trek's history of immature psychic children--Charlie X, to give one example, although Su'Kal has no idea what he's done or even that the outside universe exists. Still, I can imagine everyone being so afraid of him they'll immediately want to sedate him into unconsciousness and keep him there...or worse. Which definitely would not sit well with Saru.)
Now exposed, Tilly tries to jump Discovery away, overriding Stamet's objections. Booker says he'll take his ship and return to the nebula to pick up the away team. As he leaves, Tilly tries to go to "black alert"--but Osyraa's goons beam aboard Discovery and take over the ship, and grappling tentacles emerge from Viridian to hold Discovery in place. Stamets is subdued by some kind of mind control circlet placed on his head, and Osyraa herself beams aboard the bridge and takes the captain's chair.
Book's ship pops back above the planet with a surprise passenger--Adira, who has taken Jett Reno's badge. She beams down with extra radiation meds. We don't see her arrive, but Book calls to the away team to come on. Saru starts to ask Michael to stay behind and talk to Su'Kal, but she points out that he has to, because his Kelpien song calmed Su'Kal down. Culber says he will also stay, as he thinks he can talk to Su'Kal as well. So Michael beams back to Book's ship, and they emerge from the nebula just in time to see the captured Discovery jump away, taking the Viridian with her.
Whew. This was a lot. I don't think it was as messy and overstuffed as some, but our heroes are for sure in deep shit. What sold this for me was the performances, especially Doug Jones--who I'm sure appreciated being out from under his makeup, but even with his human face, he's still Saru. I know very little about the actor playing Su'Kal, Bill Irwin, but he definitely sold the idea of a terrified, immensely powerful child in an adult's body.
Now Osyraa is on her way to the Federation's secret headquarters (although it's rather ironic that she didn't stay around long enough to explore the nebula, as all the dilithium she could ever want was right there within reach). According to the previews, Tilly will come up with a plan to retake the ship, which hopefully will redeem her losing it in the first place. Only two episodes to go.