Birkhoff: We have a breach. __(1)__, but huge.

Percy: Do tell.

Birkhoff: Well, I was running a system diagnostic. Rerouting network traffic, using a new technique I picked up from, uh – from the engineer. Actually, the truth is, uh, if I hadn't met him, I don't know if I ever would have?__(2)__ it.

Percy: Spotted what?

Birkhoff: A shell program. Planted behind the firewall, like a?__(3)__ back door that leads from the division subnet out into the real world.

Michael: Wait. Uh, somebody hacked into our server? I thought that was impossible.

Birkhoff: No, no, it is impossible. Look. It's like a – a private chat room, ok? It's 2 ways, and none of the chats are __(4)__. So there's no way to tell how much it's been used or what's been said.

Percy: Nikita.

Birkhoff: That'd be my bet. Question is Nikita and who. The shell can be accessed from any __(5)__inside division. Anyone with the code can bring up the shell.