Impossibilities

John leaned back in his seat, staring up at the ceiling as if it contained all of life's answers. Of course, he knew it didn't, but it was still an interesting exercise, and sometimes there were amusing things to be discovered.

Once, he had seen a smear that looked suspiciously like grape jelly, though he hadn't been entirely sure, and definitely wouldn't have checked.

That had been his life. Work, which was boring, led to ceiling staring in the hopes that it would contain something that might alleviate the routine that had dominated his life the past few years.

He blinked, shaking his head slightly, and stared at the ceiling again. Was it... moving? That was impossible. There was no way the ceiling could move. Maybe if it had been that floating drop ceiling, standard in so many cubicle offices, but this wasn't your standard office building.

That ceiling should not be moving.

A low rumbling started, building up steadily until it shook the entire building, causing the chair he was in to slide from one side to the other, though he barely felt the movement.

It felt like an earthquake, but that was impossible. Earthquakes were impossible on Luna.

Alarm lights flashed on, accompanied by a wailing siren, and John bolted upright, grabbing for the shock baton attached to the bottom of his desk. That was the attack klaxon. Who the hell would be invading Luna, of all places?