WHY WE LIKE IT: The scientific mystery.
WHY WE DON'T: Too many pointless personal scenes.
REVIEW: I love Burnham's xenoanthropology skills and how they've been used on the show. There wouldn't have been a Klingon war if she'd been trusted. It's how she figured out the giant tardigrade. And here, finding some cultural context in old ruins so they can speak to the Ten-C is the perfect mission for her. The tail end of the season is essentially her Devil in the Dark or Darmok, and they've stacked the odds against her by making the aliens REALLY alien. A weird environment - the dead rock that used to be a gas giant, orbiting a star with massive artificial rings around it - promises huge Jovian whales flying through heavy gases, but they must still be recognizably "people" because they care for their young, and have responded to this cataclysm a thousand years ago in a recognizable way - by protecting their new system with a "hyperfield" so that they never feel the same pain again. I know the hyperfield was mentioned before, but I think they should have stressed it more in this episode because it's kind of matter-of-fact, but we don't really know what that term means. A slight glitch.
The Rosetta stone referenced in the title is alien pheromones found on the planet. It seems these behemoths might communicate (in part) through chemicals charged with emotional context. How to get across more complex ideas is something for the next episode, but here, even is one might raise an eyebrow at the way visible dust somehow infects airtight suits, the concept is well introduced. By giving Saru massive anxiety attacks and making sure we're reminded of his hyper-senses, we think the planet is somehow reverting him to the old days where he was genetically terrified of everything. When it starts to hit the others, there's genuine puzzlement, and it's the discovery of the nursery's love dust that brings the Eureka moment. Along the way, we get a bit of insight into the usually unflappable Detmer (though early Season 3 episodes showed her crack), how she had a tough family life, etc. Nothing Earth-shattering, but I'm always happy to see the ancillary crew get a bit more depth. But while the chemicals are a possible key to talking to the Ten-C, the question of why they would bring calamity to the galaxy when they evidently have known that pain, still hangs in the air. Burnham and Culber's last conversation on the experience of taking on the Ten-C's emotions is important. Empathy can be uncomfortable, but it's the only way to connect (Discovery's main theme), and that's very much our own era's malaise.
Meanwhile, Book and Tarka have crossed the Barrier without it taking a whole episode (I'm so sarcastic, sorry) and figuring that Discovery will make it through the hyperfield first, decide to hitch a ride. And so begins a mission to board the ship while cloaked from Zora's sensors to install a program to mask the parasitic ship on Disco's hull. Though Tarka once again can't be trusted and ends up taking Jett Reno hostage, it's really Booker who makes the most harmful decision. Turning General Ndoye is not that hard as her military mind makes her the wrong person for a first contact mission and she's already bristling about Burnham's side trip to the dead planet. She's still reasonable and extracts a promise from Book that he'll stand down if progress is made with the Ten-C. Well, we all know how well he was able to keep such a promise last time. The first info she supplies him is that Michael is back aboard and there's a scene where he's just behind a wall, but it's not just gonna be roses going forward.
My only real problem with the episode has everything to do with the flexible run time streamable shows can work with. On old television, writers and directors had to tighten things up, leave things on the cutting room floor, and so on to make an episode fit the allotted time slot. No longer. With Discovery, it's often a sin, as epilogues extend beyond the strong feelings of the climax, or in this case, caters to every single actor with scenes that don't always amount to much. So we gave Adira admitting a platonic crush on Detmer and having an awkward conversation with her when she returns from the mission. Jett Reno discussing her coffee preferences. And President Rillak admonishing Dr. Hiram for his bluntness while he reveals an interest in Ancient Earth crossword puzzles. Oooh. I can't believe any of this would have made it into an Ancient Earth television episode edit. The worst bit of padding, however, has to be Saru asking President T'Rina on a date when the next beat is Burnham telling Stamets the science team they have 25 hours to figure out the Ten-C language base. Saru is one of the better scientists aboard and he's going to take a stroll on the holodeck?! Definitely NOT the time for this subplot to get any advancement. You could say all the characters are sharing emotional content and reaching out to others - the theme of the episode - but do we need all that? Streaming allows for more characterization, sure, but those character moments should be appropriate and meaningful.
LESSON: I know it stinks, but we have to find a way to communicate.
REWATCHABILITY - Medium-High: Though I take issue with the pace of this episode, it's good Trek and we could call this Part 1 of a three-part finale.