Reese and Finch question the machine's reliability when they are asked to investigate a teenager who was killed years earlier; Finch remembers the origin of the machine.

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 goes undercover to find the threat surrounding the next person on Finch's list: a young army veteran named Joey Durban.

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.

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.

The team must figure out if a prominent lawyer orchestrated the murder of her husband or if she is being framed; Carter is spotted with Reese by her new partner.

When Reese and Finch discover that their latest POI has connections to Cold War Soviet espionage circles, they quickly learn how covert ops were handled in a world before The Machine.

The team is spread thin when a husband and wife’s numbers both come up

When the machine names a New York cabdriver as a person of interest, any of his passengers could be a part of the impending crime.

Reese rejoins Finch in New York, but when the team receives the number of a highly skilled antiquities thief, a surprising turn of events finds them planning a heist which could land them all in jail.

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.

Finch and Reese head to Atlantic City to protect the latest person of interest, an elderly gambler; Carter tries to clear another detective's name.

Finch and Reese must delve into the murky waters of international politics when they are given the number of a former government contractor who is stalking a UN diplomat. Also, an enemy attempts to gain an upper hand on Root.

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.

When the social security number of a young prosecutor comes up, Reese and Finch work together to figure out if their person of interest is the victim or perpetrator.

Reese and Finch get some help from Detective Fusco as they surveil their latest POI, Dr. Megan Tillman, while she’s on call and after hours to unravel the threat surrounding the promising young physician.

Reese and Finch have the added challenge of investigating a Person of Interest who wants nothing to do with their brand of vigilante justice.

The Machine leads Reese and Finch to Wall Street when a sharp young trader at a major investment bank becomes embroiled in a multi-million dollar financial scam.

With Finch back in the Library, Reese returns to field work, only to face his toughest case yet – protecting the privileged daughter of a Brazilian diplomat.

Reese goes undercover in an idyllic neighborhood when The Machine’s latest number sends him to the suburbs.

Finch and Reese meet their match: a tech billionaire whose curiosity and endless resources could expose their identities and ruin their efforts to save his life.

The Machine, now completely self-governed with its whereabouts unknown, resumes giving Finch its "irrelevant" numbers for people in danger, which include a U.S. naval officer in town for Fleet Week. However, with so many sailors flooding the streets of New York City, finding the officer in time presents an even bigger challenge for Reese and Shaw.

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.

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.

The Machine sends Reese and Finch to a wedding to protect a pair of POIs before their nuptials. Also, Fusco becomes angry at being kept in the dark by the team and takes it upon himself to investigate a string of missing person reports.