Discovery searches for the next clue, hidden on a Weather-Control Machine amongst a pre-warp society.
Tropes:
- Alien Non-Interference Clause: The Prime Directive looms large over the episode. Burnham ultimately breaks it: the Weather-Control Machine is going to break down sooner or later (five were installed, four have already gone) and the locals will need to learn to maintain it if they are to, you know, not die. The events of this episode also show why the Prime Directive was instituted in the first place. The Weather Control Machines were put in place to help the Halem'nites, a well-meaning gesture by the Denobulans who experienced similar adversity on their own homeworld, but it ended up making the Halem'nites dependent on the safe zones and implicitly stagnant as a culture. When people stopped showing up to maintain the towers, they inevitably broke down and the Halem'nites had to abandon their settlements. Even worse, the machines became the basis for a religious practice of Human Sacrifice, as the Halem'nites could understand what was keeping the dust at bay but not why it stopped, attributing it to vengeful gods.
- Almost Out of Oxygen: The sacrificial chamber is actually the weather tower's vacuum chamber, which means that Tilly and Ravah will suffocate to death unless Burnham talks Ravah's father into opening the door. It's a close call and medical intervention is required, but both make it.
- Clarke's Third Law: Despite the weather towers being hidden among the environment, the Halem'nites still discovered them and understand how they are connected to rainfall. They have mistakenly associated them to their gods, unfortunately organizing a Human Sacrifice ritual that serves no purpose in their function.
- Continuity Nod: The Weather-Control Machine was placed on the planet by the Denobulans, who previously featured in Enterprise, as well as an officer who was seen in Prodigy.
- "Eureka!" Moment: Ravah shows Tilly an ancient numbering system inside the High Summit, used to indicate the five towers (they're presently in #3). Tilly recognizes the fifth symbol as being the same scratches on the water vial from the previous clue, indicating that they've been searching the wrong tower.
- Fan of the Past: Kovich has a genuine (not even replicated) 21st-century legal pad that he writes on with an actual pen. He admits that he likes the feel of paper.
- Foreshadowing: The Journey is something treated as a great honor, yet those that have won it are spoken of in the past tense and Ravah's father is quite against their participation. Too late, Tilly realizes that this is because the "winners" are sacrificed to the High Summit.
- Heroic Willpower: The Journey involves a race around the High Summit. However, to recreate the ancient journey it commemorates, participants have to take a drug that induces severe thirst and run the whole distance without succumbing to the desire to drink from the various water bowls left along the path. Only Tilly and Ravah make it to the end.
- Human Sacrifice: The Halem'nites sacrifice people to the High Summit in hopes of bringing the rain.
- I Have My Ways: Kovich cryptically replies that he's "resourceful" when asked how he came by the names of the Progenitor research team and somehow acquired a genuine 21st century legal pad.
- Last Resort Takeout: With a Star Trek twist. A holographic semi-flashback shows how Dr. Culber learned that his abuela's mofongo recipe was actually horrible, and rather than serve it, she'd wait until Culber was distracted and then make a new batch using the replicator.
- Loophole Abuse: The final test of the Journey is to carry a bowl of water to the finish line without dropping it, a task made extremely difficult by the participants having run the whole race suffering from what is essentially severe dehydration. Ravah ends up spilling their bowl, but Tilly gets around that by pouring some of her own water into the bowl so they can both finish, which Ravah's father reluctantly allows.
- Lost Technology: The weather towers are archaic by modern Starfleet standards, but appear opulent and mysterious to the Halem'nites.
- The Main Characters Do Everything: Subverted, as Michael wanted to chase after Moll and L'ak but is told that a separate crew is handling that while Discovery focuses their attention on the next Progenitor clue. At the end of the episode, they are informed that Moll and L'ak have been captured, all offscreen.
- Mythology Gag: According to Kovich's note, the Betazed scientist who helped decipher the work of the Progenitors is called Marina.
- "Not So Different" Remark: Upon learning the truth of the rain towers and aliens among them, Ohvaz begins questioning his faith in his gods. Due to the theme of the season discussing Sufficiently Advanced Aliens in the Progenitors, Michael warmly comforts him that the tower having a logical explanation doesn't mean his gods don't exist, though they'll have to adjust their faith to deal with their new reality.
- Ragnarök Proofing: Averted. It's noted that the weather towers on Halem'no have to be regularly maintained, and that clearly stopped at some point (the Burn can likely be blamed). Four towers have failed completely, severely shrinking the habitable area of the planet, and the fifth is on its last legs. Burnham even notes that, while she has repaired it for now, the Halem'nites will need to be taught how to do so themselves lest it fail again.
- Rubber-Forehead Aliens: The Halem'nites look human but with markings on their foreheads arranged in a triangular pattern.
- Screw the Rules, I'm Doing What's Right!: Burnham breaks the Prime Directive to save Tilly and Ravah.
- Starfish Language: The Halem'nites have a phonetic language and a secondary language based on whistling for communication over longer distances.
- Weather-Control Machine: Halem'no is an arid world besieged by constant dust storms, protected by a weather tower that creates a verdant zone while also generating a forcefield to block the storms. Four other such towers have since fallen into disrepair.
