The Machine gives the Social Security number of a girl that has been dead for two years. Reese and Finch try to track down an apparent ghost while Finch remembers his partner's objections when he first created the Machine.
Songs: Handsome Boy Modeling School -- The Truth
Reese and Finch try to help an ex-Marine who is working with a gang of other ex-soldiers who rob banks to cover their debts. Meanwhile, Carter comes to the realization that Reese isn't the cold-blooded killer she initially believed.
Dr. Megan Tillman, a workaholic ER physician, comes up on the Machine. While Reese and Finch watch her, Fusco has to deal with a drug cartel that wants their drug money back.
When a judge's son is kidnapped, Reese and Finch try to help him. However, he isn't interested in putting his son in further danger by accepting their help.
Songs: The XX -- Intro
Reese needs to get close to a secretive woman of uncertain occupation when her number comes up. Meanwhile, Carter investigates a murder tied to the evidence theft.
A Cold War assassin goes after the members of his former team, and Reese and Finch try to stop him. Meanwhile, Fusco attempts to convince Carter that her shooter can do some good.
The Machine gives Reese and Finch Carter's number, and they are forced to deal with a number of suspects when they realize that crimelord Carl Elias has hired someone connected to her to kill her.
The Machine gives Reese and Finch four new numbers, and they soon discover that one of the Persons of Interest is already dead. Meanwhile, IA investigates Carter for her involvement with the mystery man, and the CIA tells her that they want Reese back.
Songs: Unkle -- When Things Explode
A wounded Reese recovers from his injuries, and Finch sets him up at an apartment building where the Machine has given them the super's number. Meanwhile, the CIA follows Carter in the hopes that they can find Reese through her.
Reese and Finch take on the case of a out-of-work construction foreman who is soon framed for the murder of a congressman. Finch soon discovers that he's up against a mysterious hacker who is his technological equal, and turns to former Person of Interest Zoe Morgan for help.
While Reese, Carter, and Fusco protect a young teenager out for revenge on the gangers who killed his brother, Finch worries that his dead partner's son Will will track down the woman who knows about the creation of the Machine.
Reese and Finch discover that their newest Number is a Wall Street prop trader who may be in involved in a multi-million dollar scam that will rob thousands of investors of their life savings.
Reese and Finch discover that their next Number is a six-month-year old girl who needs protection when her mother is killed and the baby is left at a clinic. To save her, Reese must turn to Elias for information despite the risks. Meanwhile, Fusco and Carter are both forced to choose sides.
Reese and Finch must deal with a new Number who has very little electronic footprint. However, they soon discover that their "client" is actually two people with the same name, SSN, and bank accounts... and one of them is in great danger.
Songs: Polica -- Amongster
Songs: Unkle -- Lonely Soul
Finch tries to keep Reese off of a case by giving him his birthday off, but Reese soon learns about it anyway and realizes it related to a personal incident in his life.
Songs: Danger Mouse & Sparklehorse -- Revenge
Reese and Finch set out to protect their newest Number, a psychologist who has been targeted for death by one of her clients. However, they soon discover their new case is anything but simple when HR, the FBI, and Alicia Corwin all come after them.