You all file into the lift quickly, just as the creature sees you and begins to rush towards you. It gives another great roar as it begins to charge. The doors begin to close slowly, much too slowly for your tastes as the creature rapidly closes the distance between you and it.
Finally, the door does close and the lift begins to rise. A large bang shakes you all to the ground as the creature slams into the metal door. There's the grinding of metal on metal as the elevator barely manages to get out. The door opens to the first floor of the vault, void of life. In the past few years, no one's ever really bothered to go up there, save for those just wanting to wander around.
Twenty feet away from the elevator is an immense steel door, shaped like a gear. In front of it is a small computer console that is dwarfed by what it controls. The number of your vault is the only thing written upon save for safety warnings.