Person of Interest2011

Harold Finch:
It's a nice office, isn't it?

Detective Joss Carter:
When you cook up a cover, you don't mess around.

Harold Finch:
John Warren is our friend's clean cover. We never use it for work. It's the most complete identity that John has, and it most closely matches the details of his true past. But John Warren is still an illusion, the incomplete footprint of a man who doesn't exist. If we make a mistake, or if Donnelly spots a single flaw, we and the work that we do will be in very grave jeopardy.