This title sounded like a snippet from a poem, so I searched for it. Of course, I came up with a quote from the Bard, from "Julius Caesar." William Shakespeare has a quote for everything.
“There is a tide in the affairs of men
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.
On such a full sea are we now afloat;
And we must take the current when it serves,
Or lose our ventures.”
In this episode, that could apply to Osyraa, who is "taking the gamble of her life" with the Federation; to Michael Burnham, who is gambling she will be able to fight her way through Discovery, Die Hard-style, to reach Stamets; to the bridge crew, led by Tilly, who are gambling they can take back the ship (and in the show's last scene, get a boost from an unexpected source); and, far back in the Verubin Nebula, to Saru, Culber and Adira, who are gambling that the Discovery can return to them before they die. (They aren't shown, which is just as well; this episode has a lot going on, and it almost felt like it was happening in real time. We'll check back with the nebula next week for the season finale, I'm sure.)
This episode was directed by Jonathan Frakes, and he did a bang-up job with it. There are two contrasting storylines: the efforts of Michael and the bridge crew to escape Osyraa's Regulators and take back the ship, and the negotiation scenes between Osyraa and Admiral Vance. Both storylines are expertly shot and edited, and the tension in the latter is just as high as the former. As a character, Osyraa is given the layers and nuance she previously lacked; she is a murderous despot, as was previously shown, but she is also realistic and pragmatic. She knows that with the Emerald Chain's dilithium running out, her empire is going to fall apart. Her proposal for the Chain and the Federation to join forces isn't as outlandish as it seems, and she makes substantial concessions, as Vance notes after he reads her manifesto. Unfortunately, the one additional thing he asks--that she be tried for the crimes she committed while leading the Chain--is the one thing she cannot give him. That hubris is going to be her downfall.
Michael and Booker admit they love each other, just before he sends her through Discovery to wreak havoc with Osyraa's forces (hopefully, this will not mean he dies in the season finale, because we do know the showrunners love to torment their star); and Tilly starts to rise to the occasion, leading the efforts of the bridge crew to break out of where they are being held and fight their way to the bridge. The "unexpected source" I mentioned earlier is the sphere data, which downloaded itself into the cute little repair bots (called DOTS-23, although they look suspiciously like Eve from Wall-E). Three of the DOTS meet the bridge crew in the final scene, where they are gathering weapons to prepare for their assault. The lead DOT says, "I am at your service. Shall we take back the ship?" (However, there needs to be rather more than three of them, I think....)
We're also introduced to a new character, the scientist Aurellio who is working for Osyraa, trying to figure out how the spore drive works. As noted elsewhere, the actor, Kenneth Mitchell, has made several appearances on various Star Trek shows, including voice work for Lower Decks. He was diagnosed with ALS two years ago. But the production team has continued to employ him, giving him a role here that mirrors his wheelchair use (although the futuristic chair simply floats). As Aurellio explains to Stamets, Osyraa gave him treatment, a chance and a life, and he feels loyal to her (but we see in the final minutes of the episode that loyalty starting to crumble, especially after Osyraa murders the Andorian Ryn). But as Stamets points out, while Osyraa may be more than she appears to be, she is also exactly who she appears to be--a ruthless tyrant.
Speaking of Stamets, his character is put through the wringer, and Anthony Rapp knocks it out of the park in his scenes. After Michael makes it to the spore drive room and frees him, he begs her to let him take Discovery back to the Verubin Nebula right there and then to free Culber and Saru. (And Adira, which he didn't know until Michael told him. Earlier, while he was talking to Aurellio, Stamets explicitly claims Adira as his daughter.) He cries, "My whole life in in that nebula!" But Michael can't do it. She knocks him out, surrounds him in an emergency force field--all the while he's throwing guilt at her, saying they only came to the future with her so she wouldn't be alone--and sends him out of the ship to be caught in a Federation tractor beam.
So now the pieces are in place for a helluva finale. I just hope the season finale carries on the quality of this episode. I had thought episode 4, "Forget Me Not," was the season's best, but this one may have just edged past it.