Although they’ve saved countless lives thanks to The Machine’s omniscience, John Reese and Harold Finch, along with lethal operative Sameen Shaw and unpredictable cyber-hacker Root now face an uncertain future. With a second machine — Samaritan — now online, the elusive team are now targets themselves, hiding in plain sight. The only thing more frightening than the ruthless Decima organization calling the shots is leaving those decisions up to an untested Machine. Facing a dangerous tomorrow, the POI team must find a way to outsmart Samaritan, an all-seeing, all-powerful artificial intelligence that’s self-governing, continually evolving and growing stronger every day.
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.
Despite not wanting to help with the new numbers, Finch's interest is piqued when the newest person of interest turns out to be a brilliant college student involved with a mysterious scavenger hunt.
Finch recruits Fusco to stick close to the latest POI, a professional 'wingman', but learning how to approach women soon becomes the least of his worries. Reese must find a way to play by the rules at his new day job. The Machine sends Finch and Root on a mysterious errand.
Reese's cover job as a detective at the NYPD becomes complicated when the young brother and sister he's protecting become targets of a gang investigation.
While Reese is forced to go to counseling for his violent tendencies, Root, Shaw and Finch try to help a new POI.
Reese, Shaw and Fusco must protect a unassuming office worker who stumbles into a dangerous conspiracy while moonlighting as fake detective. Finch travels to Hong Kong as part of his academic cover identity.
Shaw joins a team of international thieves in order to keep tabs on the latest POI, but an unexpected turn of events puts her in danger of being detected by Samaritan. Also, Finch and Root undertake a dangerous sabotage mission.
Reese volunteers as an NYPD police academy instructor in order to keep an eye on a talented young officer whose suspicious actions make him question her motives. Meanwhile, Martine – armed with information from Samaritan – hunts a member of the team.
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.
Samaritan shows its power by erasing crime from the city for a day in an attempt to force The Machine out of hiding.
Samaritan launches a cyber-attack on the stock exchange, forcing the team to risk their lives in a desperate mission to stop a global economic catastrophe.
Control, who oversees the handling of relevant numbers for the government, begins to question the methods and intentions of the Samaritan program. Also, alarming news reports of a pair of vigilantes rampaging through the Northeast begin to surface.
Root and Reese investigate a small town in upstate New York that holds the key to Shaw's location... and whether she's dead or alive.
When the Machine arranges for Finch to sit on the jury of a murder trial, he begins to suspect that a fellow juror is set to rig the proceedings. Meanwhile, Reese begins to open up to the department’s therapist.
Reese tries to protect a software programmer with a mysterious second life, but it’s unclear which side of her life the threat is coming from. Meanwhile, Claire, a young hacker whom Finch tried to protect from Samaritan, reaches out to him for aid.
Reese and Finch must protect Harper, a street-smart grifter, when her plan to steal cash from a medical marijuana dispensary goes up in smoke.
Reese and Finch try to protect a psychologist whose unorthodox methods for helping his patients find closure could cost him dearly. Meanwhile, flashbacks reveal Finch’s fragile state in the days following the bombing that killed his best friend, Nathan Ingram.
Reese must protect a bounty hunter who refuses to allow the potential threat to her life sway her from the relentless pursuit of her target. Also, Finch tries to set the plan he began in Shanghai in motion.
Reese and Finch scramble to protect a software CEO when his behavior becomes increasingly erratic following a hacker attack that reveals all his secrets and unravels his life.
Reese finds himself on a dangerous personal journey when he takes on a homicide case Detective Carter was never able to close.
Reese and Fusco get caught in the war between the two newest POIs, rival crime bosses Elias and Dominic. Also, a tantalizing clue to Shaw’s whereabouts leads Finch and Root into a possible trap, and Control goes rogue to uncover the true intentions of the Samaritan program.
Finch and Root race to save The Machine, which has been located by the rival AI, Samaritan. Also, Reese is caught in the middle of the final showdown between rival crime bosses Elias and Dominic.