Samaritan makes one last desperate attempt to preserve itself from Finch's virus, and the team go on what may be a suicide mission to stop it.
Finch breaks into the NSA to plan the virus that will destroy Samaritan... and the Machine. The only ones who can get him out alive are Reese, Sameen, and the Machine, if they can get to him in time. Meanwhile, the Machine shows Finch simulations of what the world would have been like without it.moreless
The President is tapped as the next Person of Interest, and the team finds itself receiving some unexpected help. Meanwhile, Finch goes on a roadtrip with the Machine to begin his final campaign against Samaritan.
After Finch goes to the wrong place at the wrong time, Samaritan gets a fix on him and won't stop until it captures him. The team rallies to protect their friend... but not everyone will come out alive.
The Voice uses a hapless locksmith to plant a bomb in an investment firm, in the first step of a new plan. Meanwhile, Sameen makes her way to New York and Root finds her.
Reese and Finch are trapped in a hospital ER when a superflu breaks out... and they realize that Samaritan is responsible. Meanwhile, Fusco continues his own investigation, while Sameen stages another escape.
While Root protects a radio host who has tapped into Samaritan's secret communication system, the Machine instructs her in how to use it to contact Sameen. Meanwhile, Samaritan keeps chipping away at Sameen's resolve, and Fusco realizes that Finch and Reese will never trust him with the truth.
The team's new assignment is protecting a couple on the day of their wedding. Someone wants to stop the wedding... or do they? Meanwhile, Fusco crosses paths with Bruce when the two of them investigate the new player in town, each unaware that it's Samaritan.
Samaritan is connected to the newest Number: a sound analyst who is looking into the death of a high school classmate. Meanwhile, Elias' friend Bruce demands answers concerning who murdered the crime boss.
Sameen escapes her captors and reunites with her teammates, but they soon realize that their friend may not be as free as she believes.
The team's newest Number has ties to the CIA, endangering Reese's cover when he's forced to intervene.
While Reese and Fusco deal with a backlog of Numbers, the Machine starts giving out false Numbers after its recent reboot. Worse, it flags three of the team members as threats due to their violent histories, and locks Finch and Root out of the system.
Reese and Finch try to get the case containing the Machine's damaged code to the station so that they can decompress it. Meanwhile, Fusco deals with the aftermath of Dominic and Elias' shootings, while Root tries to dodge Decima's agents without the Machine's help.