At precisely the time when they were expected, on the road that circled the campus, a herd of predator machines marched past the guard house. In unison, they looked down at the guard house, and then up the hill.

Immediately, in military formation, they swerved and advanced on the place where Helen sat drawing.

There was a terrifying noise of metal against metal, followed by an otherworldly howling, as if they were a pack of alien wolves on the hunt.