Haunted House Adventure – Knock

You give the ol’ shave-and-a-haircut knock and pause. A moment goes by before you hear two more knocks in a “two-bits” kind of way on the other side of the door before it swings open and a gust of wind blows you and Casey inside.

Once inside, the door swings shut behind you, leaving you and Casey in the dark. A faint radiance comes up from the wooden floor where you see a large letter “G” outlined in a white glowing paint.

You can make out a ratty couch against the back wall, and a staircase to the right of it. There’s a door to your left that hangs on one hinge and an empty doorway to your right.
You hear what sounds like shuffling footsteps from the floor above you.

What do you do?