The Machine gives Reese and Finch the number of a down-and-out man who has been pushed too far, and they're forced to turn to former Person of Interest Zoe Morgan for help.

When The Machine gives them the number of a mob enforcer whose life becomes endangered, Reese and Finch must decide whether to intervene or allow karma to balance the scales of justice. Meanwhile, Finch seeks aid from an unlikely source.

Reese is abducted by a former acquaintance planning a massive and potentially deadly act of cyber-warfare.

Finch infiltrates a tech corporation to gather intel on an executive whose number has come up; Carter questions Beecher's integrity.

The number comes up for an Internet entrepreneur in the business of eliminating people's privacy, but finds his own being rapidly stripped away. As his life spirals out of control, Reese tries to protect him while Finch calls on Shaw, Carter and Fusco for help finding whoever is after him.

Flashbacks to Finch’s adolescence provide insight into his creation of The Machine. Also, the team receives the number of an already dying man, and Reese leaves the POI team behind in the aftermath of the war with the crime organization, HR.

Reese poses as a Secret Service agent to get close to the latest POI, a U.S. congressman who may hold the key to derailing Decima’s plans to bring a second Machine online.

Forced to take on new identities provided by Root, the team members try to adapt to their new lives. However, some find it hard to ignore The Machine's numbers, which puts them all at risk of being detected by Samaritan.

Reese must save Elias from the Brotherhood. He can't get any help from Root or Shaw since Shaw's cover is blown and Root is escorting her to underground.

Reese finds himself on a dangerous personal journey when he takes on a homicide case Detective Carter was never able to close.

Reese’s cover could be blown when he realizes the latest POI has ties to his old CIA colleague, Kara Stanton.

As Reese and Shaw race to catch up with Finch, he infiltrates a maximum-security government facility in a desperate mission which could mean the end for not only Samaritan, but for himself and The Machine as well.