When they are given the Social Security number of a teenager who was killed two years ago, Reese and Finch begin to question the infallibility of The Machine. Meanwhile, Finch flashes back to The Machine's origin and how it was developed.
When the Machine produces the social security number of a judge renowned for his tough sentencing, Reese and Finch have the added challenge of investigating a POI who wants nothing to do with their brand of vigilante justice.
Mr. Reese goes as the new driver of fixer Zoe Morgan in order to decide if she's a victim or perpetrator. When Zoe listens to a recording she isn't supposed to, she becomes the target of a pharmaceutical company.
Reese works the computer while Finch does the legwork with their latest POI, a building super who keeps too close an eye on his tenants. Meanwhile, Detective Carter may finally get her long-awaited glimpse into a case.
When Carter finally comes face-to-face with Reese, he urges her to join forces to help with their latest POI, a scrappy young woman from the wrong side of the tracks who turned her life around and became a lawyer.
The Machine identifies Darren, a teenager whose brother was just murdered, as the next POI. Meanwhile, Finch is growing concerned that the son of his former business partner is dangerously close to finding out about The Machine.
Finch and Mr. Reese are going after a person who seems to be leading a double life. However, they soon realize there are 2 people with the same social security number; one of whom is in danger and one who's an impostor.