Season 2, Episode 11
"The thing about the world is that it doesn't have any extra pieces. It's like pi, it contains everything. You remove a single piece... no circle."
With Reese now in FBI custody, Carter takes it upon herself to ensure that he is not identified as the Man in the Suit. Meanwhile, the numbers never stop coming in, so Finch heads back to school
as a substitute teacher and enlists Detective Fusco's help to protect the latest POI; a teenage computer genius.
Tropes present in this episode include:
- Alcoholic Parent: Caleb's mom.
- All Up To You: With Reese in FBI custody, it's all up to Finch and Fusco to save the numbers from Irrelevant list, and it's up to Carter to make sure the FBI doesn't discover his identity.
- Alternate Company Equivalent: Caleb is basically a younger Finch while his teacher fills in for Nathan Ingham. Even Finch sees the similarities.
- Applied Mathematics: According to Finch, all of the world’s infinite possibilities are contained within the mathematical constant 'Pi.' He also states that his phone number is contained somewhere in the first 3000 digits.
- The Dog Was the Mastermind: That new drug lord that's been dealing drugs at the high-school? It's Caleb.
- Mouthful of Pi: This one was obvious just based on the title, though it was downplayed more than usual.
- Mundane Made Awesome: Finch's explanation of Pi is an in-universe example.
- Not so Fast, Bucko!: It looks like Reese is about to be released from prison. Not if Donnelly has anything to say about it.
- Obfuscating Stupidity: Caleb is really a Teen Genius whose computer coding skill impress even Finch, but he intentionally gets low grades to hide it.
- Shrouded in Myth: Mention is made of the greatest hacker of all time, a genius who hacked the Arpanet in the 70s, ultimately causing it to become the internet of today rather than a government controlled network, and got away with it because the government could never identify who did it, much less catch him. As foreshadowed, It was Finch.
- Slipping a Mickey: Carter does it to her date at the bar; she just needs to get his DNA though.
- Talking Down the Suicidal: Finch for Caleb.
- What Happened to the Mouse?: The subplot concerning Caleb's conflict with a local gang for running a drug operation in their turf is never resolved.
- Fusco tells Finch over the phone that he'll take care of it; we'll just have to assume that he did.