Doctor-Donna

"I can't believe we're right back where we started from. How did you know there was a security elevator on the top floor?" Donna laid the egg back on the table they'd just stolen it from. The heavy vault door was closed. "What if they seal us in?" "They can't," the Doctor said. "That's why we couldn't get in. Build a completely impenetrable front door, then put in a slightly less impenetrable elevator at the back. I noticed it when we were here earlier. I told you those codes would come in handy." "You were only in here for two seconds!" "Yeah, well. Best place to be right now. They won't be looking for us here. Now. Let's take a closer lo