It's Fleet Week in New York City, making the hunt for one Naval Officer among a sea of sailors even more difficult for Reese, Finch and Shaw.

The head of an Internet company ostensibly for finding lost loved ones is really a front for selling personal info. Carter has to train a new cop while she looks for Beecher's killer and a new vigilante named Collier makes his appearance.

The team suspects the latest number to be a potential stalker/ killer until he's nearly shot on the street. Root plots her escape from the institution and gives her psychiatrist a big surprise.

The next number the machine dispenses is for Vanessa Watkins, a hard-nosed prosecuting attorney who, when Finch and Reese first meet her, has just reported her husband, Jeremy Watkins, missing from their yacht. While Vanessa has put away many a criminal over her storied career, Jeremy has let many go as a flashy and high-priced defense attorney. As her number came in after the report of him missing, they know Jeremy's presumed death is not the reason for the number, yet they don't know if Vanessa is the target or the perpetrator. They learn that the lead investigator on the case of Jeremy's death, Detective Cameron, is looking at her for her husband's murder as all evidence found thus far implicates her. Cameron's main problem?: he doesn't have a body, and thus needs Vanessa to confess to make a conviction stick, which she may or may not know. They will also learn that Cameron has a personal vendetta against her, which places a major obstacle in tracking her as she tries to elude Cameron. As Finch and the team wade through the story of the complicated lives of Jeremy and Vanessa - including their unlikely personal coupling - they find that Vanessa knows her law and is resourceful and strategic in her every surprising move. They may not learn if she is the target or the perpetrator without getting the story directly from her. Even then, as she is a lawyer who knows how to spin, they have to act the judge and jury in their own court of opinion in evaluating her story. Meanwhile, as Carter assists them on this case, she finds that she has to be careful around her new rookie partner, Laskey. She doesn't yet know how careful she truly has to be.

Shaw is tasked with staying close to a 10-year-old girl identified by The Machine. Meanwhile, Carter's continues her mission to take down HR.

Root reappears and kidnaps Shaw. Finch helps an estate investigator who looking into the death of his step brother. A new vigilante group (Vigilance) makes it presence known. Carter's young partner has his loyalty to HR tested.

A hypnotherapist, who's really a con man, pumps his patients for personal information while they are hypnotized. One of his patients is an antique dealer who launders money for HR.

Finch receives 38 numbers at once from the Machine. He discovers they are connected to an unknown player who is inciting an all-out war between HR and the Russian mob.

Danger closes in when the epic battle to bring the criminal organization HR to justice reaches new heights. And when the Machine suddenly gives out Reese's number, the POI team faces their greatest threat yet.

The team seeks justice for Carter's murder, but Finch realizes that one person may go too far in the battle against HR. Meanwhile, NYPD officer Patrick Simmons' number comes up.

Flashbacks to Finch's adolescence provide insight into his creation of The Machine. Also, the team receives the number of an already dying man, and Reese leaves the POI team behind in the aftermath of the war with the crime organization.

Sameen, Harold, and Arthur make their escape. Root is captured and tortured. The others go to recover Arthur's back up hard drives but are caught in the crossfire when Vigilance arrives to claim them for themselves to expose Samaritan.

Reese, still angry and racked with guilt over Carter's death, is sent on a flight to Europe, following cryptic instructions that lead him to a POI and fight for survival while trapped on an 8hr flight.

Reese rejoins Finch and Shaw for a case involving a Olympic gymnast turned event planner.

Finch goes undercover in an emergency call center to protect a 911 operator, who's being forced to cooperate with the kidnapper of a young boy. Before long they find out they connected to a murder Fusco is investigating.

A flashback to the early days of Finch's operations reveals secrets and connections with far-reaching implications.

The Machine tasks Root to find a janitor who has a mysterious past. However, when her presence endangers him, the Machine sends his number to Finch as well.

The team gets involved in a case of international politics when a former government contractor stalks a U.N. diplomat. Meanwhile, an adversary tries to take advantage of Root.

Reese and Shaw go to a H.S. reunion to shadow a prosecutor who may have been involved in a killing 20 years ago. Finch and Fusco compete with the FBI to find out why a government employee was killed. And not far behind is Vigilance.

Reese poses as a Secret Service agent to get close to the latest POI, a U.S. Congressman who may hold the key to derailing Decima's plans to bring a second Machine online.

Decima hunts down Reese and Shaw using Samaritan's feeds. Meanwhile, Greer sets a trap for Finch by targeting his former fiancée, Grace.

While Reese and Shaw search for Finch and a way to stop Decima, The Machine gives them 5 new numbers.

The team takes desperate action in its race to prevent Samaritan from coming online and making them its first targets. Meanwhile, the months-long battle with the anti-surveillance terrorist group Vigilance comes to a shocking conclusion.