Season 3, Episode 11:
Harold: It came to you as well.
Arthur: Yes. I told them the only way they could achieve what they wanted was to build something that not only watched but understood what it was watching.
Harold: An A.I.
Arthur: I know you always said artificial intelligence was a fool's errand, Harold... I was this close.
After Carter's death has been avenged, Reese hangs up his suit and drops off the map to drown his sorrows, leaving Finch and Shaw behind to safeguard their latest number, Arthur Claypool, a friend of Harold's from college, now a retired NSA programmer whose terminal brain cancer does odd things to his memory - sometimes he can't remember things at all, and sometimes he blurts out what he now remembers no matter how classified it is to whoever's around.
The flashback scenes of the episode show a young Harold (and yes, that really is his name, though a surname is never mentioned in those scenes) growing up in Iowa with his increasingly forgetful father, demonstrating his talent for taking things apart, breaking into computer systems and expressing a desire to make a machine that can genuinely think.
Tropes present in this episode include
- 10-Minute Retirement: Finch debates quitting after Carter dies and Reese runs off to Colorado. Only the prospect of Shaw running around without supervision stops him.
- Air Vent Infiltration: Shaw uses the false ceiling to enter the radiology lab.
- Alma Mater Song: Finch sings one with Arthur.
- Ambiguously Evil: Look closely at the end. Hersh's box is yellow (knows about The Machine), and not red (relevant threat).
- Animal Motifs: There's a birdcage in Finch's boyhood home, and as a boy he was always asking his father to identify birds.
- Battle in the Rain: Fusco going Good Old Fisticuffs with Reese.
- Beard of Sorrow: Reese has the "unkempt stubble" version.
- Beneath the Mask: Control has to reveal herself after Arthur reveals that his wife has been dead all along.
- Bilingual Bonus/Genius Bonus: the word "lethe" in Greek literally means "oblivion", "forgetfulness", or "concealment."; perfectly suited to Arthur Claypool's predicament.
- In ancient Greek mythology, it was the name of the underworld's "river of forgetfulness." If you drank water from the River Lethe, you forgot everything.
- Cliffhanger: The episode ends with Control holding Arthur and Finch at gunpoint, saying that the one who discloses the location of their Magnum Opus machine gets to survive. The Machine starts calculating some probabilities; specifically:
- Death, 46.18%: Arthur T. Claypool
- Death, 43.68%: Admin
- Death, 84.98%: Sameen Shaw
- Death, 26.50%: Robert N. Hersh
- Death, 11.65%: Control
- Continuity Nod: Arthur mentions that Samaritan was shut down on February 25, 2005. According to the flashback in "Super," Alicia Corwin told Nathan Ingram that the first "number" The Machine gave the government had turned out to be accurate the day before that, on February 24, 2005.
- Dark Reprise: "Diane Claypool" has her own musical theme, which turns gloriously sinister when her identity as Control is revealed.
- Dead Person Impersonation: Control is Diane.
- Dead All Along: Diane Claypool.
- Drowning My Sorrows: Reese. Subverted when Fusco does it with club soda.
- Exact Words: Reese tells Fusco to sit at the bar and drink. He didn't say anything about drinking alcohol, so Fusco orders water - because he's now a teetotaler.
- Right after the first 1979 flashback, as Finch, Shaw and the Claypools exit the elevator, for less than a second, you can see a red square around Diane Claypool, indicating she's a threat.
- Arthur remembers Harold, but not his own wife. His wife has been Dead All Along...
- In the Bayesean probability tree The Machine is constructing at the end of the episode, there is a yellow box that reads "RETASKING ANALOG INTERFACE."
- The book Finch fetches for Root: False Gods, Pseudepigrapha In The Modern Age.
- The music changes when Samaritan is first mentioned, cuing the audience to its importance.
- Freeze-Frame Bonus/Rewatch Bonus:
- When Root puts the three books together to make Arthur's number, and admonishes Finch that he should stop ignoring The Machine, the green book in the middle is called Remembering the Tabulator.
- "Sameen Shaw" is an alias, according to the Machine's probability tree at the end of the episode. Her real name is redacted.
- Gambit Pileup: Hoo boy. Vigilance attempts to kidnap Arthur, but are foiled by Finch and Shaw. At the same time, Arthur's wife Diane is really Control in disguise, who was keeping an eye on Arthur in an attempt to find Samaritan. Oh, and whatever Control is up to has gotten her designated with a red box.
- Get A Hold Of Yourself Man: Fusco tries this on Reese, but it's not very successful since Reese is a significantly better fighter than Fusco, despite having a good deal of whiskey in his system.
- Heroic BSoD: After the events of the HR subplot, Reese goes through one and goes to drink himself to death in Colorado.
- I Coulda Been a Contender!: Arthur said that he only needed a few more weeks before the government shut down Samaritan, and he could have done what Finch did - created an Artificial Intelligence of his own.
- Labcoat of Science and Medicine: It helps that Shaw actually is a doctor.
- Meaningful Echo:
- In the flashbacks, Finch's father has a degenerative memory disorder, with effects similar to what the brain tumor is doing to Arthur.
- As a little boy, Finch wanted to build a machine to preserve his father's memories from being wiped out—just as The Machine did when it created the "external hard drive made of people and paper" to preserve its memories from its nightly reboot.
- Missing Mom: Harold's mother is never mentioned in any of the flashback scenes.
- Newspaper-Thin Disguise: Fusco staking out Reese's bar, who isn't impressed.
- Oh, Crap!:
Shaw: Is he talking about what I think he's talking about?
- Shaw's face is priceless when she figures out who "Diane Claypool" really is.
- Subdued, as you would expect from him, but Harold's reaction to finding out what Samaritan is:
Finch: It would appear so.
Shaw: But then that would mean
Finch: That there was a second Machine... and Arthur built it.
- OOC Is Serious Business: Finch ignoring calls from the Machine and Reese not stopping a man from getting beat up.
- Refused the Call: Literally in Harold's case, as he walks past a row of ringing phones.
- The Call Knows Where You Live: So the Machine contacts Root instead, despite her living in a Faraday cage that should make communication impossible.
- Remembered Too Late: Justified due to Claypool's memory problems.
- The Reveal: Samaritan is not as destroyed as the Machine thought it was.
- Reality Ensues: Shaw is a formidable former government assassin who can deal with almost all threats to Harold and Arthur. However, when a numerically superior force who have had the same training as her go up against her (Control's security detail), she is easily outnumbered and taken out of play.
- Shout-Out: Though it's not the first time the show has done it, Harold walking past a row of payphones as each of them ring in succession is reminiscent of Neuromancer.
- Shown Their Work:
- In one of the flashback scenes a teenaged Harold gets a pay phone to connect him to a random number in Paris (with a period-accurate dial tone!) for free using a plastic whistle. This was an actual method of phone phreaking during that time period, which was most commonly known to be used by John Draper, AKA Captain Crunch.
- The transistor memory circuit Finch built in 1971—not only is it possible to build one out of transistors, the prop they built actually works.
- Similar Squad: Collier has his own female gunslinger who exchanges shots with Shaw.
- Stealth Hi/Bye: Shaw on Finch, as usual.Finch: Must you do that?
- Take That!: to the NSA's real-life surveillance program PRISM—Arthur says it's a kludge used only as a decoy to keep people from discovering the truth about The Machine.
- The Machine itself designates PRISM as a decoy.
- Tampering with Food and Drink: Someone spikes the Chinese food of the Secret Service detail.
- Teen Genius: Harold in The '70s.
- The Teetotaler: Turns out, Fusco became this after working with Reese.
- Truth Serum: Claypool is injected with sodium pentathol under the guise of his MRI scan.
- Understatement: Finch's reaction to finding out that Samaritan was one of the Machine's contenders:Finch: Sounds like quite a project.
- Verbal Backspace: Shaw makes her "Talk is overrated" comment when she's supposed to be offering a sympathetic ear to Diane.
- Wham Episode: The entire premise of the show changes with this episode, as it becomes much less case-by-case and now becomes centered on the war between two artificial intelligences; The Machine, and Samaritan.
- Wham Line:
- "There is a second Machine."
- "I remember Diane. Diane is dead. I buried her two years ago."
- In-Universe; Hersh addressing Diane as a superior, making Shaw realise she's the Control she wanted to meet back in "Relevance".
- What the Hell, Hero?: Root gives one to Finch about his deliberately ignoring messages from the Machine. No explanation was given as to how she got Arthur's number without leaving the Faraday cage.
- We Need a Distraction: Finch has to restrain Shaw's enthusiasm. "I'm sure there are ways to get to Claypool that do not involve any form of combustion!"