Binky fought for height, rising nearly vertically with his hooves thrashing the air and his breath curling away behind him like a vapor trail. Mort hung on with knees and hands and mostly with willpower, his face buried in the horse’s mane. He didn’t look down until the air around him was freezing and thin as workhouse gravy.

Overhead the Hub Lights flickered silently across the winter sky. Below—

—an upturned saucer, miles across, silvery in the starlight. He could see lights through it. Clouds were drifting through it.

No. He watched carefully. Clouds were certainly drifting into it, and there were clouds in it, but the clouds inside were wispier and moving in a slightly different direction and, in fact, didn’t seem to have much to do with the clouds outside. There was something else…oh yes, the Hub Lights. They gave the night outside the ghostly hemisphere a faint green tint, but there was no sign of it under the dome.

It was like looking into a piece of another world, almost identical, that had been grafted on to the Disc. The weather was slightly different in there, and the Lights weren’t on display tonight.

And the Disc was resenting it, and surrounding it, and pushing it back into non-existence. Mort couldn’t see it growing smaller from up here, but in his mind’s ear he could hear the locust sizzle of the thing as it ground across the land, changing things back to where they should be. Reality was healing itself.

Mort knew, without even having to think about it, who was at the center of the dome. It was obvious even from here that it was centered firmly on Sto Lat.

He tried not to think what would happen when the dome had shrunk to the size of the room, and then the size of a person, and then the size of an egg. He failed.

Logic would have told Mort that here was his salvation. In a day or two the problem would solve itself; the books in the library would be right again; the world would have sprung back into shape like an elastic bandage. Logic would have told him that interfering with the process a second time around would only make things worse. Logic would have said all that, if only Logic hadn’t taken the night off too.