As the Federation and the Discovery comes to terms with the destruction of Kwejian, the crew must confront the strange anomaly that destroyed the planet and figure out what it is and where it's going next.
Tropes:
- All for Nothing: It turns out that the anomaly can change direction without external impetus, making it virtually impossible to anticipate where it's going to go, which renders much of the trouble spent trying to study it in this episode pointless.
- Asteroid Thicket: The anomaly has a chaotic belt of asteroids — probably pieces of Kwejian and its moon, as Stamets somewhat tactlessly notes — which Book has to dodge.
- Astronomic Zoom: Just in case being told the scale of the anomaly didn't do it justice, the final scene of the episode zooms out from Discovery to show the anomaly utterly dwarfing a planet, then an entire solar system, and finally past several more to demonstrate the sheer reach of its devastation.
- Bittersweet Ending: Discovery has the beginnings of an explanation for the anomaly, but it is also even more incomprehensible than they initially assumed and there's no way to predict where it will go next.
- Brick Joke: When Stamets first boards Book's ship, he tries to make small talk by asking if Book feels any tingling when operating the spore drive interface. After they've exited the anomaly, Book admits that he does.
- Call-Forward: Discovery's computer is now formally calling herself Zora, yet another step towards her becoming the entity in "Calypso".
- Central Theme: Post-Dramatic Stress Disorder. The episode is shaped heavily by death, loss, and trauma:
- Stamets is trying to get over his Non-Action Guy role in the prior season's finale, feeling guilty over his complete inability to save his family (Culber, Adira, and Grey) and a little bit resentful of Book for doing it instead.
- Tilly is affected by the death of the Mauve Shirt Cmdr. Nalas in the previous episode.
- Adira is too, but mostly because it reminds them of how Grey died.
- And, of course, Book just saw his planet destroyed, and his Death Seeker mentality drives the episode.
- Continuity Nod: Culber notes that the procedure for giving Grey's consciousness a new body is derived from the research of a 24th-century cyberneticist named Soong, and the new body that he built for some admiral-- "Picard was his name."
- The Dead Have Names: Burnham identifies the other two people killed besides Commander Nalas during the rescue mission as Lt. Aloka and Ensign Neville.
- Death Seeker: Book is driven to investigate the anomaly at any cost, out of guilt for not seeing the destruction of his world coming or rescuing his family before it happened.
- Declining Promotion: Saru is offered the position of captain on the Sojourner, but declines because he feels that his place is on Discovery during this crisis.
- Dude, Not Funny!: Lampshaded by Stamets when he makes a Thrown Out the Airlock joke around Burnham, given that that was a sore point between them last season. Though he's gotten over it, he acknowledges that the joke was in poor taste.
- Easily Forgiven: Stamets makes a joke about shooting him out into space, getting looks from everyone around. It's quite clear that he's calmed down from being pissed off at Burnham over that stunt. In fact, he's actually angrier at himself for not being able to save his family at the time.
- Good News, Bad News: Tilly informs Burnham that she has good news and bad news. The good news is that she and Adira have managed to predict the gravitational waves. The bad news is that the next one will hit two seconds from now.
- Gravity Screw: The Artificial Gravity aboard Discovery is overwhelmed twice during their study of the anomaly as gravitational waves impact the ship, causing the crew to float helplessly for a few seconds until the system adapts. Nilsson warns after the second time that, if they get hit again, the generators will blow out for good.
- Hallucinations: Book sees the birds from his homeworld among the debris in the dust cloud, and his nephew running through the ship, which distracts him at a crucial moment of potential escape. Burnham has to talk him back to reality on a private channel.
- Heroic BSoD: Book spends much of the episode in a daze, unable to process the destruction of Kwejian or the deaths of Kyheem and Leto.
- He's Back!: Saru rejoins Starfleet, retaking his commission as captain, though he declined being captain of the U.S.S. Sojourner over returning to the Discovery as its First Officer.
- Innocently Insensitive: Stamets notes aloud that the anomaly's Asteroid Thicket is probably a result of it recently passing through a planetary system before cutting himself off, having remembered whose planetary system it was.
- Last of His Kind: Since they can't seem to find anyone else, Book has become this for his race. Justified as the Kwejian were a pre-warp species until very recently, and thus didn't have much of an off-world presence.
- Mildly Military: Saru rejoins Discovery's command crew as Burnham's Number One (which the series seems to have mistaken for a formal term for First Officer) despite being a Captain with more seniority than Burnham and thus her superior in any real military organisation.
- The Needs of the Many: Burnham faces this when she's rightly concerned about Book's suitability for the mission, a fact not helped by his insistence that he needs to do something, regardless of her orders. Saru points out that, emotional instability aside, Book is correct that he is uniquely qualified to undertake the mission, convincing Burnham to let him go with Stamets tagging along as a remotely-controlled hologram. Later on, when the subspace gravitational waves force Discovery to pull back, Burnham is tempted to drag Book to safety with the tether, but also has to acknowledge that pulling him out early will only force them to try again and potentially lead to more deaths, forcing her to reluctantly choose to let him finish.
- Negative Space Wedgie: The titular anomaly is speculated to be a strange sort of binary black hole, casting gravitational distortions over a five-light-year area as the two collide and consume one another. When investigated, however, it lacks any evidence of dual singularities and can change course absent any apparent external force, leaving only more questions as to what it is.
- Oh, Crap!: Tilly explaining to Saru that, for some unknown reason, the anomaly changed its course, meaning that it could do so again at any moment and there's no way to predict its course or who it might threaten.
- Person as Verb: Tilly describes herself as "Stamets-ing" when she snaps at Adira during the crisis.
- Plot-Driven Breakdown: Book tells the holographic Stamets to disconnect so they can start analyzing the data, only for Stamets to admit that the same thing causing distortions in his holo are also blocking the transmission of the data to Discovery, meaning that the only way they get the information is to fly back out of the anomaly.
- Pop-Cultural Osmosis Failure: Saru doesn't get the meaning of "swagger" or a reference to Mount Everest as an expression of vast size. Understandable for the former, though you think he'd have run into the latter during his time at Starfleet Academy.
- Recycled Title: A first for the Star Trek franchise, this episode shares its title with an episode of Star Trek: Enterprise aired 18 years earlier.
- Remote Body: Burnham has Stamets join Book as a hologram controlled through a neural link, allowing him to be physically present to conduct the scans of the anomaly while only risking one of the two people capable of operating the spore drive.
- Super Prototype: Admiral Picard's android body is retroactively established to be this. Most of the attempts after him to move a consciousness into an android body didn't take, and the research was ultimately abandoned due to poor results. Culber thinks that Gray, having already succeeded in maintaining his consciousness within the symbiote, has a good shot of beating the odds.
- Surprisingly Realistic Outcome: Burnham tries to guide Book through a precise manoeuvre to escape the anomaly. The first time that she calls for him to go, he hesitates and asks her if she's sure. She says yes and he goes, but by then, a good five or ten seconds have passed; instead of talking being a free action, the moment is lost. Fortunately, he gets a second shot and trusts her unconditionally, getting the timing right and escaping with the data.
- Wham Line: "It changed direction?!"
- What the Hell, Hero?: Tilly snaps at Adira when the latter gets overconfident in their work, Tilly asking them to double and triple check it. Culber calms Tilly down, letting her know that Adira looks up to her and they're just trying to impress her. Tilly makes up for it by praising Adira's performance after the situation is resolved.
