Recap: Person Of Interest S 02 E 21

Season 2, Episode 21:

Zero Day

"Can you hear me?"
The Machine.

After ten days of silence, the Machine gives Finch and Reese the number of Ernest Thornhill, a mysterious tech millionaire whose true identity is not what they expected. With fewer than 24 hours left until the virus infecting the Machine goes live, time is running out as old and new enemies appear, old secrets are revealed, and Reese and Finch find themselves forced to accept help from some unexpected allies as they race to stop the threat against Thornhill's life.

Tropes present in this episode:

  • Are We There Yet?: Finch compares Reese's frequent inquiries about whether the Machine has given them a new number to this.
  • Armor-Piercing Question: Nathan gives one to Finch: "Do you even remember your real name, Harold?"
  • Brain Uploading: Ernest Thornhill's data entry company is doing this for The Machine, so it can preserve non-relevant memories from its nightly reboot. Root, who is horrified, calls it "an external hard drive made up of people and paper."
  • Call Back: Several, but most notably:
    • Nathan's comment to Finch in a flashback—"Nothing is ever simple with you, Harold."—echoes the conversation between Reese and Finch in the diner in "Judgment."
    • A "Panther platform" sedan built by Ford Motor Company flips over on its roof in a crash, as occurred in "Pilot" and "Firewall."
    • The episode ends with a shot of Reese answering a pay phone call from The Machine like he did in the season 1 finale, "Firewall." His posture and facial expression are identical.
  • *Click* Hello: This is becoming a bit of a running gag between Reese and Shaw.
  • Crazy-Prepared: Reese reveals that he planted a tracking device on Finch's glasses at one point because he doesn't want to risk losing another person that he cares about.
  • Death from Above: A highly innovative version. A assassin uses an RC UAV packed with some explosives and flies it into the sedan the POI is being chauffeured around in.
  • Declaration of Protection: Reese promises Finch that he won't let Root get to him again. So of course then Finch sends him out to do some bogus recon work and goes to meet Root anyways.
  • Dirty Coward: Averted with Greer. When Shaw and Reese are killing off his security detail, he's calmly finishing off some paperwork he's been examining, calmly talks with the two Bad Ass Assassins who have every reason to kill him and when reinforcements arrive, slips away.
  • Enemy Mine: Finch ends up having to team up with Root to protect the Machine.
  • Facial Dialogue: Reese engages in some fantastic non-verbal communication when Shaw asks if he is able to track down Finch.
  • First Name Basis: Root tells Finch to call her by her assumed name. After hearing this, Harold continues to address her as "Ms Groves."
  • Frame-Up: Carter is framed for shooting an "un"armed man.
  • Freeze-Frame Bonus: At the very end of The Machine's reboot sequence, there's a block of binary code. If you convert it to ASCII, it reads Quis custodiet ipsos custodes—Latin for "Who watches the watchers?"
  • Genius Bonus: Finch says the Machine deletes itself and "reinstantiates 1.618 seconds later" every midnight. 1.618 is the "golden ratio."
  • The Ghost: Ernest Thornhill, whose name is a Shout-Out to two other famous works involving an invented person, The Importance of Being Earnest and North By Northwest.
  • Idiot Ball: The big mook has a knife under John's throat and... instead of killing him, just waits until John kills him instead. Reminds of infamous Darth Maul vs. Obi Wan suicide-by-inaction scene.
  • I Have Your Wife: Finch agrees to go with Root after she explicitly threatens Grace.
  • Indy Ploy: "This is the plan."
  • Lampshade Hanging: Nathan hangs a lampshade on Finch's tendency to choose bird names for aliases.
    Nathan: Are you sure [Grace] is ready to become Mrs.... Ostrich?
  • Noodle Incident: Nathan alludes to whatever events caused Finch to take on a new identity in the first place, implying that he would be charged with sedition and mayhem.
  • Offscreen Moment of Awesome: Nathan Ingram, middle-aged engineer and businessman with no combat training, saving the lives of five people, with little more than a handgun and a sense of justice.
  • Perma Stubble: Reese has been sporting this during the past few episodes.note 
  • Special Edition Title: The opening credits malfunction due to the problems with the Machine.
  • Tearjerker: Everything about the flashbacks. Everything.
  • Title Drop: Harold gets awfully close to it in one of the flashbacks.
    "...So technically it would still be day zero."
  • Wham Episode: That is all.
  • Wham Line:
    • "Ernest Thornhill is the Machine!"
    • "Can. You. Hear. Me?"
  • What the Hell, Hero?: Finch gets one from Root, of all people, after explaining what he did to limit the evolution of the Machine's AI. She shows far more emotion over this than she has over any of the five people she's known to have murdered.
  • When the Clock Strikes Twelve: The virus is set to go live at midnight.
  • Written-In Absence: Fusco was absent from "Zero Day" and "God Mode", and Carter mentions early on that it's because he is working a case elsewhere.
    • Real Life Writes the Plot: Kevin Chapman landed roles in two feature films, and wasn't available when the last two episodes of Season 2 were being shot.