The spiral staircase goes round and round. Take two steps up and one step down. Take a rest now and then. The railing is there.
The earthquake is calling. You fall. In the darkness going down, you see light at the bottom of the shaft, and realize that in the tumult, your bearings were lost, and you are hurling up, not down.
You pop out the top, into the light. You have landed on solid ground. You look down the spiral staircase and notice that it is nothing but a shaft of light.