Person of Interest2011

Root:
So if you're like me, and we both know you are, you designed the Machine so that a catastrophic crash puts it into a remote debugging protocol; a God mode that gives the admin full access to all of its data. That's what Decima's after. And that's why they wanted to kill Thornhill. He was buying up all the pay phones in Manhattan, but they stopped him. I don't know about you, but I don't really want to see what happens when an evil multinational becomes omniscient. But why you would leave it so vulnerable? You made the machine to protect everybody. What did you do to it that it can't protect itself? [Harold is silent] Let's try something simpler. How vulnerable is it?

Harold Finch:
After the virus crashes the machine, whoever answers its call will have unfettered access for 24 hours.

Root:
Which pay phone is it going to call?

Harold Finch:
I'm not really the trusting sort, Ms. Groves, and Decima cannot possibly know that information.

Root:
I think they know enough, Harold. They're guarding every pay phone in midtown. So It must be somewhere around here.