This is a bit of a transitional episode. Now that Discovery has found what's left of the Federation and more or less settled in, the question is: What happens now? How will they be used by Starfleet? How will the crew fit in, and how has Michael's year alone in this new world affected her? She accepted Saru's offer to be his first officer--given her history, will she be able to live up to that? And what's going on with Georgiou?
Three weeks have passed since Discovery came home, and the ship has now been fitted with 32nd century technology. Some of this seems pretty damn wobbly, and only there to show off the CGI and look pretty--detachable nacelles? Really? How does that even work? "Programmable matter" consoles that stretch out when the crew pulls on them like blue nanogel taffy? Bah. I'd still want my touchscreens, thank you, even if that left me a hopeless backwards Luddite. (Linus the Walking Sinus must agree with me, as a running gag throughout the episode is that he can't master his personal transporter badge and keeps popping into places he didn't mean to. One hopes he doesn't mistakenly beam inside the bulkhead.) The bridge crew, of course, geeks out with delight, especially Tilly. They are playing with their new toys when a ship hails them from outside the Federation distortion field--and the signal shows a large purring Grudge, Book's cat, pawing at the camera.
We find out via prerecorded hologram that Book has tracked down a lead on one of the "black boxes" of starships destroyed during the Burn. Michael wants as many of those black boxes as she can get to determine what happened, and Book tells her he had gone to the planet to fetch it. He says if he doesn't return within 24 hours, his ship will seek out Michael on autopilot to tell her what's going on. This was three weeks ago, and nothing has been heard from him.
(Just how Book knew where to send his ship, since the secret coordinates were supposedly only in Adira Tal's memory, is left as a gargantuan exercise in plot holes for the viewer.)
Of course, Michael immediately wants to go haring off after him. Saru slaps her down, and for good reason: during his first briefing with his fellow Starfleet captains, he discovers that Starfleet's hold on its planets and territory is far more fragile and tenuous than anyone knew, and the Andorian/Orion criminal syndicate, the Emerald Chain, is shaping up to be quite dangerous. (And during this meeting, in a touching nod I'm not sure got noticed, one of the other ships is named the Le Guin.) Now that Discovery's refit is finished, Admiral Vance has ordered him to be on standby, ready to jump into the middle of a possible situation on the planet Argeth at a moment's notice. So Saru orders her to keep preparing the crew for that possibility.
Naturally, in a callback to a certain captain's "The answer is no. I am therefore going anyway," Michael goes to Philippa the Merciless and asks her to go on an "unsanctioned mission." Georgiou points out that she is essentially cutting Saru's legs out from under him, which gives Michael not a minute's pause. (Honestly, Michael doesn't come off too well in this episode.) Georgiou doesn't care, of course--as she says, "You had me at 'unsanctioned mission.' " So the two of them take off in Book's ship. On the way there Philippa teases Michael unmercifully about her feelings for Book, which Michael denies way too strenuously. But Philippa also goes into another of her fugue states, in which we see a flash of a bloody knife, see her hands drenched with blood, and hear her moan someone's name: "San." Michael tries to ask her what's going on, but Georgiou refuses to talk about it. They arrive at the planet, and the avatar of its Orion administrator, Tolor, shows up on the bridge, and Georgiou relieves her frustrations by ripping the poor guy a new one (or I would say "poor," but he's later shown to be a murderous tyrant). She says she has dilithium to sell, and she and Michael go down to the planet and its combination mining operation and junkyard bazaar, pretending to search for odd pre-2400 parts while looking for Book.
Michael's absence is eventually discovered by Sylvia Tilly, in a delightful little scene where she goes to Michael's quarters and finds only one huge cat. Despite Tilly's protestation that she's "not a cat person," Grudge walks all over her. (That cat really is big. She's got to weigh at least thirty pounds, from the looks of her.) Later, in engineering, while Tilly is playing with her new badge's projection abilities, Saru corners her and asks her if she knows where Michael has gone. He realized as soon as she came up absent what she is probably doing. (Which makes me wonder why he didn't impound Book's ship or something, since he surely could have predicted that Michael would take off in it. Maybe he was hoping against hope that she wouldn't pull the same sort of stunt that she did on the Shenzou [at the beginning of Season 1] again? But he must suspect that Michael hasn't changed, and in fact, her year alone in the future has made her even less likely to respect the chain of command. Which also makes me wonder why he asked her to be his Number One in the first place....) Tilly gives him an insightful piece of advice: he should be the one to tell Admiral Vance what Michael has done, as Discovery still has to prove themselves and it will reflect badly on them if the Admiral finds out from anyone else. Saru agrees. (This is a very nice scene.)
Back on the planet, Georgiou and Michael find Book. He's been made a slave in the mine/junkyard, along with many others. The one the episode focuses on is Ryn, an Andorian who tried to stand up to the planet's crime boss, Tolor's aunt Oryssa, and got his antennae hacked off for his trouble. The slaves are kept under control by an implant in the backs of their necks that triggers the perimeter fence and chops their heads off if they try to escape, as shown in a rather gruesome demonstration the sadist Tolor puts on for Georgiou's benefit. While Georgiou stalls and haggles, Michael and Book are reunited and come up with a plan. Georgiou jury-rigs a controller to take out the fence, and she and Michael let themselves be captured by Tolor in order to be taken to the control room. Meanwhile, Book arranges a distraction in the form of the slaves pretending to rush the fence. Michael, Tolor and Georgiou fight, and Philippa goes into one of her "states" in the worst possible moment. She recovers in time to grab the controller and power down the fence, and everyone rushes to escape--Georgiou and Michael to Book's ship, and the other prisoners to a transport just outside the perimeter. Ryn is shot protecting Book as they rush across the junkyard, and Michael beams them aboard. (I expected him to die, but they get him back to Discovery and manage to save him.) They also use Book's ship to mow down all of Oryssa's personnel and blow up the complex, in a bit of calculated murderousness which perfectly fits Georgiou's character but was more than a little appalling coming from the show's purported star, Michael Burnham. (I would make a bet that this doesn't get mentioned again or dealt with, and it absolutely should be.) Michael also insists that Georgiou tell her "what happened down there," and Philippa admits that these flashbacks, or whatever they are, have been happening for a couple of weeks and are getting worse. (Were they triggered by her interrogation in the previous episode somehow?) Michael asks why Georgiou didn't come to her, saying they're not in the Terran Empire anymore and a vulnerability isn't a death sentence, and tells the Emperor she can trust her. Georgiou rejects this, saying Mirror Michael said much the same thing, and it was a lie.
Back on board Discovery, Michael has to face the music. On the way to meet Admiral Vance, Book stops the turbolift so he can thank Michael for saving his life, and they start kissing. (Following a brief interruption by Linus, popping into the turbolift on his way to the science lab. I rather imagine those turbolifts are going to get a bit rusty, as no one will need to use them anymore....) Admiral Vance reads her the riot act, saying the only reason she's not in the brig is because she saved lives, and leaves her ultimate punishment up to Saru. In a rare Star Trek instance of someone's defying direct orders and suffering consequences (at least someone in the opening credits), Saru relieves her of First Officer duties and busts her back down to science officer. For whatever it's worth, Michael tells him he did the right thing.
This bit of heaviness is offset by a delightful B-plot: we see more of Adira Tal and her ghost-lover, Gray, and get some more Adira-Stamets bonding. Stamets is complaining about the refit and how it's completely upset his engine room, and Adira shows him how she's changed the spore drive interface (turning it into more of that icky nanogel taffy) to make it easier for him to operate. Later, Adira is sitting in the mess hall eating and talking to the invisible Gray, and Stamets notices. He sits with her and gets her to open up about what's going on, saying that because of what happened with him and Hugh, he believes her. After this, Stamets and Hugh are discussing it in their quarters, and Stamets say that because he never thought he'd meet another person who had the same experience he did, loving someone who died and came back, he wants to help Adira. These are more nicely written and well-acted scenes.
So now we've got an uneasy status quo re: Discovery and Starfleet, and Michael at a bit of a crossroads: what's she going to do now? I think it's a fair bet that whatever's going on with Georgiou will figure heavily into this. This episode isn't as good as the previous "Forget Me Not," but so far, the level of quality for this season has definitely been raised.