animal that was gaining savvy and determination, and that was somehow frightening.

From far off to the west, toward the forest and the river, came the laughter and the howling of a pack of screamers. Duncan leaned his rifle against the boulder and got up to pile more wood on the fire. He stared out into the western darkness, listening to the racket. He made a wry face and pushed a hand absent-mindedly through his hair. He put out a silent hope that the screamers would decide to keep their distance. They were something a man could do without.

Behind him, a pebble came bumping down the slope. It thudded to a rest just short of the fire.

Duncan spun around. Foolish thing to do, he thought, to camp so near the slope. If something big should start to move, they'd be out of luck.

He stood and listened. The night was quiet. Even the screamers had shut up for the moment. Just one rolling rock and he had his hackles up. He'd have to get himself in hand.

He went back to the boulder, and as he stooped to pick up the rifle, he heard the faint beginning of a rumble. He straightened swiftly to face the scarp that blotted out the star-strewn sky—and the rumble grew!

n one leap, he was at Sipar's side. He reached down and grasped the native by an arm, jerked it erect, held it on its feet. Sipar's eyes snapped open, blinking in the firelight.

The rumble had grown to a roar and there were thumping noises, as of heavy boulders bouncing, and beneath the roar the silky, ominous rustle of sliding soil and rock.

Sipar jerked its arm free of Duncan's grip and plunged into the darkness. Duncan whirled and followed.

They ran, stumbling in the dark, and behind them the roar of the sliding, bouncing rock became a throaty roll of thunder that filled the night from brim to brim. As he ran, Duncan could feel, in dread anticipation, the gusty breath of hurtling debris blowing on his neck, the crushing impact of a boulder smashing into him, the engulfing flood of tumbling talus snatching at his legs.

A puff of billowing dust came out and caught them and they ran choking as well as stumbling. Off to the left of them, a mighty chunk of rock chugged along the ground in jerky, almost reluctant fashion.

Then the thunder stopped and all one could hear was the small slitherings of the lesser debris as it trickled down the slope.

Duncan stopped running and slowly turned around. The campfire was gone, buried, no doubt, beneath tons of overlay, and the stars had paled because of the great cloud of dust which still billowed up into the sky.

He heard Sipar moving near him and reached out a hand, searching for the tracker, not knowing exactly where it was. He found the native, grasped it by the shoulder and pulled it up beside him.

Sipar was shivering.

"It's all right," said Duncan.

And it was all right, he reassured himself. He still had the rifle. The extra drum of ammunition and the knife were on his belt, the bag of rockahominy in his pocket. The canteens were all they had lost—the canteens and the fire.

"We'll have to hole up somewhere for the night," Duncan said. "There are screamers on the loose."