The first few seconds of the episode start with a Caveziel (John Reese) love scene. You already know it is bound to have ended badly... he's a hobo. An ass kicking hobo.
Quickly enough, he get's in jail for having beaten thugs. Only to get mysteriously bailed out by Emmerson's Finch. He refuses an offer to use his CIA/BLACK-OPS acquired skills to protect people who are about to die/commit murders.
Next thing you know, John Reese wakes up handcuffed to bed having to hear a murder not being able to prevent it. Sure enough it was a recording played by Finch and Reese can't help but realize : He'll save People of Interest.
Reese's girlfriend died when he was halfway across the world on a mission.
They were together in 2001 during the twin towers attact. (that much for a timeline)
Finch was working for the government a program to treat the data (phones, cells, e-mail...) given by the patriot act. The goal was to prevent any new terrorists attacks. Probable events were classified in two categories : relevant (to mass murders) and irrelevant (smaller events).
The machine was to destroy the lists of irrelevant items every night at midnight. Finch worked out a backdoor to send the Social Security numbers (9 digits) of people at the center of irrelevant events. That's it they only got a number and a name to work on. Anymore data and the leakage would be found.
Finch used to have a bank (who failed) and someone close to him died. It is probably why he choose to work on the irrelevant list.
The Government thinks both John and Finch are dead.
They have a cop who suspect Reese, a crooked cop working for Reese in the inside and a general conspiracy.
I will be more severe of the show for the next ep. I just do think the pilot lives to his premise.