Horror story

The Next Door

Without hesitation, you fling the door open and jump through. The door slams behind you and disappears. You turn to the new scene before you. It looks like a museum.
You walk up to one of the display cases. You see a flash of your reflection in the glass and look away, but it is too late.
"First I crawl,
Then I stand,
Then I lean,
With help from my hands."
You search around the room. There seems nothing particularly helpful, but you know there must be an answer. You see a torch on the floor, and bend down to pick it up. Your hand brushes something. You find it is some kind of poster. You pick the torch up and examine it. It is a poster, of the different stages of man. First is a baby, then an adult, then an old man. Yes, this must be the answer.
First I crawl - As a baby, obviously.
Then I stand - An adult
Then i lean, with the help of my hands - that's an old man leaning on a walking frame.
Easy, you think, and you again see the door appearing. You drop the poster and the torch, and go.