Saru communicating with the Pahvans.
The Discovery is assigned to try to find a way of negating the Klingon's cloaking advantage by using an apparently natural energy coming from the planet Pahvo. Cornwell is interrogated by L'Rell, but L'Rell reveals that she wants to defect and help Cornwell escape.
Tropes in this episode include:
- Action Prologue: The Discovery and the Gagarin battling the Klingons.
- Better to Die than Be Killed: Cornwell takes the initiative when she and L'Rell are caught escaping, grabbing L'Rell's knife and starting a fight. L'Rell overpowers and kills her, noting that it's a better death than what she would get otherwise.
- Blatant Lies: When Kol catches L'Rell in a hallway with Cornwell, L'Rell beats the crap out of Cornwell and claims that she tried to escape. It's an obvious lie, and Kol is not fooled.
- The Bus Came Back: L'Rell returns, bearing the scars that she received during Lorca's escape, offering to interrogate Cornwell for Kol.
- Captain's Log:"Personal log, Specialist Michael Burnham, Stardate 1308.9. We landed on Pahvo eighteen hours ago. It's a seemingly uninhabited planet, but a unique and, for us, strategic one. Every tree, rock, and blade of grass here vibrates with its own specific tone. Together these combine to form a kind of music, the signature sound of the planet heard everywhere on the surface. The sound is even broadcast into space by a towering crystal structure, a sort of naturally-occurring transmitter. It is Starfleet's plan to modify the electromagnetic frequency of Pahvo's signal and harness it as a form of SONAR that can detect the presence of cloaked Klingon vessels decimating our fleet, make them visible to our sensors, and turn the tide of war in our favor."
- Chekhov's Gun: Burnham explains early on that Saru's species can run up to 80 kph, which would allow him to make it to the antenna in about 15 minutes. When he learns that Tyler is trying to stall him so Burnham can modify the antenna to contact Discovery, he's able to reach her before she can finish the job, even though she had a considerable head start.
- Cliffhanger: The Discovery finds itself in the Pahvo system with the Sarcophagus arriving, and L'Rell is being hauled off to be executed.
- Cow Tools: L'Rell brings in a rack of unpleasant-looking bladed implements for her interrogation of Cornwell, but it's just to make the guards think that she's serious about the torture.
- Curb-Stomp Battle: The Gagarin and the Discovery are no match for six Klingon warships, with the Gagarin destroyed and the Discovery forced to retreat. To make it worse, the Hoover and the Muroc were already destroyed off-screen.
- Desecrating the Dead: L'Rell stumbles on a room filled with the bodies of her former friends, some mutilated, and vows revenge on Kol for their murder.L'Rell: Grafk. Torath. Silrek. I will end Kol. I will avenge you all. I swear it to you.
- Enemy Mine: L'Rell teams up with Cornwell to escape from the Sarcophagus, since she wants to defect to the Federation, but is forced to kill Cornwell when they're caught to protect herself.
- Energy Beings: The Pahvans communicate through spore-like constructs that take humanoid form.
- First Contact: Saru, Burnham, and Tyler make first contact with the previously unknown inhabitants of Pahvo.
- Genius Loci: Everything on the surface of Pahvo is one interconnected living being.
- Gratuitous Latin: The title means "If you seek peace, prepare for war" in Latin. It comes from the writings of Publius Flavius Vegetius Renatus.
- Gunship Rescue: The Discovery attempts to come to the rescue of the USS Gagarin, but fails to save the other ship.
- Heroic Sacrifice: Cornwell starts the fight with L'Rell knowing that there was no way that they'd be able to escape. By attacking L'Rell, Cornwell would give her cover to explain away what they were doing.
- Holding the Floor: Tyler has a philosophical talk with Saru to stall for time while Burnham modifies the transmitter. Saru is pissed when he twigs on and rushes to stop Burnham.
- I Am the Noun: A third-person variant regarding the Pahvans.Tyler: Are they native to this planet?
Saru: They are the planet. - I'm Standing Right Here:Burnham: [to Tyler] Kelpiens pursued by apex predators have exceeded speeds of 80 kilometers per hour. They can also sense predators from as much as ten kilometers.
Saru: And we particularly enjoy being discussed in the third person while present. - Innocent Aliens: Burnham is convinced that the Pahvans are inviting the Klingons and Federation to Pahvo in order to talk out their differences and have no idea what the Klingons are likely to do to them.
- Invisibility Cloak: Kol has spread the Sarcophagus cloaking tech to much of the Klingon fleet, giving the Klingons a decisive advantage in the war.
- Kneel Before Zod: When L'Rell tries to leave Kol's presence, his soldiers stop her and force her to turn around and kneel before him.
- Loophole Abuse: When Saru claims that the Pahvans are willing to offer the team whatever they want, but intends for them to never leave, Tyler decides that the modification to the crystalline antenna falls under that umbrella and orders Burnham to do so.
- Mercy Kill: L'Rell kills Cornwell to cover her own attempt to defect, but also to spare the admiral from further imprisonment and torture.
- More than Mind Control: Saru attempts to sabotage the mission, not out of malice or because he's being controlled, but because for the first time in his life he's somewhere that he isn't afraid and doesn't want to lose it.
- Mythology Gag:
- Burnham and Tyler have a "Needs of the many/Needs of the few/Needs of the one" conversation.
- It is mentioned that Starfleet has no death penalty, indicating that the events of this episode occur before Captain Pike and the Enterprise visit Talos IV
.
- Obfuscating Stupidity: Kol initially appears to have accepted L'Rell's explanation for Cornwell's "escape" and accepts her loyalty, but eventually makes it clear that he hadn't bought any of it.
- O.O.C. Is Serious Business:
- Inverted here, as Tilly is worried about Stamets now that he's not acting out of character, i.e. he's returned to being the Jerkass that he was prior to the gene therapy.
- Played straight with Saru. It turns out that his complete lack of concern should have been a huge red flag.
- Organic Technology: The Pahvans have a subspace transmitter made from a giant tree laced with crystals.
- Pardon My Klingon: While talking to Cornwell, L'Rell describes Kol by using that time-honored Klingon insult "petaQ'".
- Superweapon Surprise: The Klingon fleet's widespread adoption of the cloaking device is enough to reverse the gains that the Federation had made courtesy of the Discovery's spore drive. Even their trademark Hyperspeed Ambush proves entirely insufficient to help them defeat ships that can cloak and uncloak at will.
- Take a Third Option: Stamets's argument about why he can't tell Culber about the mental effects of the spore drive: if he tells him, Culber would be forced to report it, and Stamets would be hauled away for testing. If Culber doesn't report it and Stamets is found out, Culber's career would be ruined. By not telling Culber, Stamets is sparing his partner from having to make the choice.
- Taking the Bullet: Lorca orders the Discovery to get between the Klingons and the Gagarin, intending to intercept two torpedoes fired at the latter, but only manages to stop one while the second destroys the Gagarin.
- Talking Is a Free Action: Averted. If L'Rell and Cornwell hadn't stopped to chat in the middle of making their escape, they wouldn't have been spotted by Kol happening to walk by the other end of the corridor.
- Teleportation Sickness: A variation— Stamets is clearly feeling the strain from using himself as the key component of the spore drive.
- That's an Order!: With Saru emotionally compromised, Tyler pulls rank on Burnham and orders her to complete the mission as planned.
- Unstuck in Time: It's hinted that the tardigrade therapy has done this to Stamets. After exiting the chamber, he briefly wonders why Captain Tilly is present, before getting his bearings and denying that he was confused.
