The episode begins with a flashback to April 5th, 14 years ago. The day the Synths revolt on Mars. The technicians that didn't get the day off for the holiday (First Contact day) working alongside a synth F8. It's apparent, these androids are not as advanced as Data, awkwardly conversing with the techs, and similar to Data (pre-emotion chip), has no understanding of humor (some of the dialog here also seems out of place for Star Trek, like the use of terms like "Hell yeah". It's a little too... 21st century). It's apparent somebody hacks F8, causing it to activate/corrupt the other synths, and deactivate/turn the planet defenses against Mars, before killing everyone in the room and shooting itself in the head.
Back in the present day... Picard, Laris and Zhaban review the security footage, which only shows Picard on the roof and the explosion. Dahj and the Romulan troops are somehow missing from all the footage. Zhaban suggests the Tal Shiar may have altered the footage, but Laris has another theory... She tells Picard of the Zhat Vash, a secret organization within the Romulan Tal Shiar (really!? a secret organization
within essentially a secret police? I'm sorry, but that's just dumb writing, and these writers need to stop with the secret organization plotlines) which keeps a secret so "profound and terrible" that it can "break a person's mind" (whatever that means). Zhaban doesn't believe they actually exist, saying it's just a "boogyman" story told to new recruits and children. But Laris believes they do, and claims they are the reason we've never seen Romulans pursue artificial intelligence, cybernetics and androids (despite an episode of TNG
contradicting this, not to mention, I've always gotten the impression their computers are on-par with Federation computers, which utilize a degree of AI, so I just can't buy that they don't pursue AI technology) because they have a deep loathing for artificial life... for some reason (and if they're going out of their way to get to Dahj and Soji... why didn't they ever go after Data?). Picard and Laris go to Dahj's apartment, trying to use a Romulan device (which is considered illegal in the Federation because it's considered... unreliable? Although Laris claims that just want they want them to think) to recreate the scene, but antileptons prevent them from seeing anything after the moment Romulan soldiers beamed in. Searching for the whereabouts of Soji, they look through Dahj's files and discover a communication from her, sent via subspace, meaning she's somewhere in space.
Picard calls in a friend from his days on the Stargazer to give him a medical check up to declare him fit for duty (what about Beverly? or Pulaski?). The doctor however tells Picard he found a problem with the porialtal lobe in his brain (Irumodic Syndrome?), but Picard is still able to persuade him to clear him, suggesting the mission may kill him first. The next day, Picard goes to Starfleet Headquarters to explain the situation and asks to be reinstated, but the admiral (rudely) denies the request following the interview he gave in the previous episode, pointing out 14 worlds had threatened to leave the Federation if they continued to help the Romulans. Returning home, Zhaban suggests he gets help from his former crew, like Rike, Worf, or Geordi (good to know he wasn't killed in the android revolt, given the comic book established Geordi was in charge of building the fleet at Mars). Picard says he can't, knowing they'd do it, but he doesn't want to put them in harms way. So instead Zhaban suggests he needs someone that hates him and has nothing to loose, to which Picard says he already put in the call... His former first officer from the evacuation efforts, Raffi Musiker. She agrees to help him after he tells her secret Romulan assassins are operating on Earth.
Meanwhile, we see the admiral that denied Picard's request to be reinstated contacts Commodore Oh (I'm pretty sure she's the first commodore we've seen in Star Trek since the original series) to apprise her of the situation. Oh, a Vulcan(?), it turns out is involved in the Romulan plot to hunt down the androids, along with a Lieutenant Rizzo, which is a surgically altered Romulan to look human. "Rizzo" turns out is also Narek's sister, so no surprise he's a bad guy as well.
Few other things of note... Apparently following the destruction of Romulus, there is now a Romulan Free State. It is unclear if it is a new government, replacing the Romulan Star Empire, or a separate government. At any rate, the Romulan Free State runs the operations of the captured Borg cube, which may explain why they seem to be more open about joint operations with the Federation. And Romulans with the forehead ridges are in the show. The Borg cube has gone 5843 days without an assimilation, which is about 16 years. It isn't clear how/why this cube was disconnected from the Collective, but I've been seeing speculation it may have been the result of Admiral Janeway's pathogen. Dr. Jurati has only been able to find any information on Dahj's identity going back about 3 years, suggesting the two "androids" are only about 3 years old. And while in the lobby of Starfleet Headquarters, Picard looks overhead to a holographic display of famous Starfleet ships the first being the Discovery version of the Enterprise, which then switches to the Enterprise D.