Once Jack stepped through the door, everything was as he had seen from outside, darkness. Complete darkness. He was unsure of where to go since he could not see anything. He turned around and found that the door he had come in from had disappeared.
'I didn't hear the doors getting closed,' he thought as he extended his hand out to touch the door. There was nothing. He only took one step through the door, no way he couldn't touch the door. He walked back several steps with his two hands stretched out like a blind man walking to prevent himself from bumping into the wall, but there was nothing at all.
Suddenly dim light illuminated his surroundings. He could see things now. Yet, there was also emptiness as far as his eyes could see.
'This is familiar,' Jack thought after seeing the surroundings. This place was a constructed dimension like the one he had fought Eldingar in.