He turned to go back to the elevator. A section of the ceiling four inches wide slid down to become a wall, in front of him, ceiling down to floor. Zi-ip : that fast. It was a transparent wall, plastic but thick, and he knew he’d never be able to break it. He stared, feeling a panic of the sort he hadn’t felt since having his first really bad childhood nightmares. He touched the wall to be sure it was real.