An ex-CIA agent and a wealthy programmer save lives via a surveillance AI that sends them the identities of civilians involved in impending crimes. However, the details of the crimes, including the civilians roles, are left a mystery.
A billionaire software-genius named Harold Finch creates a Machine for the government that is designed to detect acts of terror before they can happen, by monitoring the entire world through every cell-phone, email and surveillance camera. Finch discovered that the machine sees everything, potential terrorist acts and violent crimes that involve ordinary people. When the government considered violent crimes between normal people "irrelevant", Finch built a back door into the system that gives him the social security number of a person involved in a future violent crime so he could act. Partnered with John Reese, an ex-CIA agent, the two work in secret to prevent violent crimes before they can happen. Eventually their activities lead to being hunted by the New York Police Department, CIA Agents in pursuit of Reese who was listed as dead, a computer hacker named Root who wants access to the Machine, and government officials who want to keep all knowledge of the Machine a complete secret.
Wealthy genius software engineer, who generally goes by the name Harold Finch, is the mastermind behind the creation of an all-seeing machine. Finch and his front man Nathan Ingram devised the machine to sell to the US government, who are unaware of Finch working behind the scenes. The purpose of the machine is so that the government can spot acts leading to terrorism to prevent those terrorist acts from occurring. But what the government considers irrelevant in its use of the machine are acts leading to murder. As such, Finch, without the governments knowledge that he has a back door to the machine, wants to prevent those murders. The machine only provides the social security number of someone involved, Finch unaware if that person is the target or perpetrator. He enlists the help of an ex-CIA special operative who generally goes by the name John Reese to assist in his mission, Reese who is officially listed as dead. But as Reese in particular often uses non-legal means to achieve Finchs end goal, he is tracked by the authorities, who only know him as the man in the suit. They are also tracked by those who are thwarted by the pair in carrying out this mission, and by the few who know of the machines existence and who have their own nefarious thoughts of what to do with the machine if they can get their hands on it.