Finch and Reese team up with unexpected allies as they race to fix the machine; as Detective Carter tries to apprehend Cal Beecher's murderer, she finds herself up against HR -- a criminal organization.

When a virus causes the machine to malfunction, numbers are issued irregularly; the team searches for an extremely elusive tech millionaire.

When a person of interest is poisoned, Finch and Reese only have 24 hours to identify the toxin and find the person responsible; Detective Fusco's past catches up to him.

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

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.

As Finch and Reese try to protect six people simultaneously, clues lead them to a coastal town; when a storm forces Finch and Reese to seek shelter in a police station with a group of locals, they realize a killer may be in their midst.

A lethal government operative who tracks and stops terrorist threats before they occur finds herself on the run – and the new focus of Reese and Finch's attention. However, their pursuit proves to be their most formidable when they discover that her remarkable skill set equals their own.

As Reese and Finch try to save a hotel maid's life, they encounter a litany of suspects; Detective Carter considers a significant offer from the FBI.

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.

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

Carter tries to help Reese by engaging in mental warfare with the FBI; Reese has encounters with old and new enemies; Detective Fusco must protect supermodel Karolina Kurkova, the latest person of interest.

Finch goes under cover to protect a youth who reminds him of himself; Carter goes on a dangerous mission for the FBI.

As the FBI pursues "the man in the suit," Reese is even more determined to protect the latest person of interest after learning she is the sister of a soldier who was killed in action.

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.

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

The Machine gives Finch and Reese the number of a brilliant surgeon, but they soon discover that a resourceful third party has raised the stakes for this POI, forcing them to turn to an unlikely source for help.

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

Reese must protect an investigative journalist through surreptitious means to avoid becoming part of her story.

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.

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.

The Machine delivers the number of a cold case that leads Reese ever closer to catching up with Finch and his kidnapper, Root.

With Finch missing – kidnapped by his hacker nemesis, Root, Reese enlists Detectives Carter and Fusco to get his friend back, Meanwhile, The Machine never sleeps, disseminating a new number to Reese.