On this week's Person of Interest…
Kara kidnaps Reese and orders him and Agent Snow to follow a list of demands or face being killed.
Reese and Snow infiltrate a building that houses a secret set of D.O.D computers containing viruses, malware, etc.
Reese tries to stall and erases all the bad programs, but Kara wanted to install a cyber virus instead.
Kara leaves the two men to die.
Agent Snow plans on returning to the CIA, but after Reese tells him there's no way, he sacrifices himself to kill Kara.
Kara wanted to figure out who sold the computer that started the whole mess, and a new organization that wants to help tells her to implant the bad hard drive.
The person who sold it is Harold Finch.