To combat Root and Decima, Reese and Finch must seek out unusual allies to save The Machine. Meanwhile, HR prepares to eliminate Carter when she probes into Cal's death. And in the past, the final fate of Nathan is revealed.
The Machine becomes increasingly erratic because of the computer virus, and Reese and Finch must find an elusive tech millionaire. Meawhile, Carter puts herself at risk when she tries to find Cal's killer.
The newest Number is a famous cardiologist, but by the time Reese gets to the man, it's too late: he's already been given a slow-acting irreversible poison. While Reese and the doctor try to track down the man who poisoned him, Carter has a tough decision to make when IAB moves in on Fusco for the murder of his partner a year ago.moreless
While Carter tries to determine if her boyfriend is working with HR or not, Finch infiltrates a tech corporation to determine if their new Number is trying to help the company or hurt it.
While Carter deals with corruption within her own department, Reese and Finch help an elderly gambler and try to figure out why the mob wants him dead.
Reese and Finch head off to a small coastal town when The Machine gives them the Numbers of six missing people. When a storm moves in, they are trapped at a police station with several locals... and one of them is a killer.
Reese and Finch must help their new Number, a counter-terrorist operative who is on the run from her own people.
Reese and Finch attempt to protect Mira, a hotel maid with a long list of enemies. Meanwhile, Carter gets a job offer due to her help in the "man in the suit" case.
Reese and Finch try to help a billionaire tech magnate only to discover that doing so may compromise their existence when he sets out to find out who they really are and what they know.
Reese's former partner Kara abducts him as part of her scheme to unleash a wave of cyber-terrorism across the world and get revenge on the people she believes wronged her.
While Carter tries to maintain her cover as an FBI temporary agent while helping Reese, Fusco has to protect a new Number on his own while Reese ducks some old enemies from the past.
The team's newest Person of Interest is a teen genius and Finch goes undercover as a substitute teacher to protect him. Meanwhile, Carter takes on her first assignment as a temp agent for the FBI.
As the FBI renews their hunt for Reese, he and Finch try to help a sister of a dead soldier seeking justice for wronged veterans.
Reese and Finch must track a cab driver whose Number has come up... but they don't know if he's involved or if one of his passengers may be the intended victim or predator. Meanwhile, Simmons continues to put pressure on Fusco.
The team has to protect two Persons of Interest when the Machine gives them the numbers of a husband and wife.
Reese and Finch set out to protect a surgeon who has come up as their newest Person of Interest. However, when they discover that someone from Reese's past is involved, they turn to a former Number for help.
Reese is off to the suburbs to take on an undercover assignment to protect the newest Number.
Reese must protect an investigative journalist without letting her know that he's around, for fear of blowing his and Finch's cover.
Reese and Finch must decide whether to help a mob triggerman who is their newest Number, or leave him to his well-deserved fate.
Reese returns to field work and must protect the spoiled daughter of a Brazilian diplomat.
In Texas, Reese and Carter investigate the disappearance of a 14-year-old girl from over a decade ago that may lead them to Finch and his abductor.
Reese and the Machine join forces to track down Finch, who has been abducted by the mysterious Root.