You feel down the door frame from all sides. All you find is a key, and a package of gum with an expiration date from 10 year ago. The key is small, and silver. It has a marking that says, “16-43-19”. You wonder what this could mean, but you start hearing footsteps coming from down the hall, and see two bright red eyes staring at you. The eyes disappear into the darkness, leaving you with two choices.

You try the key on the door.
You walk down the hallway.