She was not hurt, but the jolt brought her to her senses: the jolt—and something else.

In falling, she had thrown her arms out to protect herself, and as her head cleared she realized that there was no earth beneath her fingers, only emptiness. She lay there, not caring to move.

“Sue, where are you?” It was Colin’s voice, calling softly. “Are you all right?”

“I’m here. Be careful. I thinkI’m on the edge of a cliff, but I can’t see.”

“Keep still, then:!”ll feel my way to you.”

He crawled in the direction of Susan’s voice, but even in that short distance he partly lost his bearing, and it was several minutes before he found his sister, and having done so, he wriggled cautiously alongside her.

The turf ended under his nose, and all beyond was a sea of grey. Colin felt around for a pebble, and dropped it over the edge. Three seconds passed before he heard it land.

“Good job you tripped. Sue! It’s a long way down. This must be the old quarry. Now keep quiet a minute, and listen.”

They strained their ears to catch the slightest sound, but there was nothing to be heard. They might have been the only living creatures on earth.

“We must go back to the path, Sue. And we’ve got to make as little noise as possible, because whatever it is that made this fog will be listening for us. If we don’t find the path we may easily walk round in circles until nightfall, even supposing we’re left alone as long as that.

“Let’s get away from this quarry, for a start: there’s no point in asking for trouble.”

They stood up, and holding each others hand, walked slowly back towards the path.

As the minutes went by, Susan grew more and more uneasy.

“Colin,” she said at last, “I hadn’t run more than a dozen steps,I’m sure, when I tripped, and we’ve been walking for a good five minutes. Do you think we’re going the right way?”