throaty roll of thunder that filledthe night from brim to brim. As he ran, Duncan could feel, in dreadanticipation, the gusty breath of hurtling debris blowing on his neck,the crushing impact of a boulder smashing into him, the engulfingflood of tumbling talus snatching at his legs.

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

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

  Duncan stopped running and slowly turned around. The campfire wasgone, buried, no doubt, beneath tons of overlay, and the stars hadpaled because of the great cloud of dust which still billowed up intothe sky.

  He heard Sipar moving near him and reached out a hand, searching forthe 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 bagof rockahominy in his pocket. The canteens were all they had lost--thecanteens and the fire.

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

  * * * * *

  He didn't like what he was thinking, nor the sharp edge of fear thatwas beginning to crowd in upon him. He tried to shrug it off, but itstill stayed with him, just out of reach.

  Sipar plucked at his elbow.

  "Thorn thicket, mister. Over there. We could crawl inside. We would besafe from screamers."

  It was torture, but they made it.

  "Screamers and you are taboo," said Duncan, suddenly remembering. "Howcome you are afraid of them?"

  "Afraid for you, mister, mostly. Afraid for myself just a little.Screamers could forget. They might not recognize me until too late.Safer here."

  "I agree with you," said Duncan.

  The screamers came and padded all about the thicket. The beastssniffed and clawed at the thorns to reach them, but finally went away.

  When morning came, Duncan and Sipar climbed the scarp, clambering overthe boulders and the tons of soil and rock that covered their campingplace. Following the gash cut by the slide, they clambered up theslope and finally reached the point of the slide's beginning.

  There they found the depression in which the poised slab of rock hadrested and where the supporting soil had been dug away so that itcould be started, with a push, down the slope above the campfire.

  And all about were the deeply sunken pug marks of the Cytha!

  IV

  Now it was more than just a hunt. It was knife against the throat,kill or be killed. Now there was no stopping, when before there mighthave been. It was no longer sport and there was no mercy.

  "And that's the way I like it," Duncan told himself.

  He rubbed his hand along the rifle barrel and saw the metallic glintsshine in the noonday sun. One more shot, he prayed. Just give me onemore shot at it. This time there will be no slip-up. This time therewill be more than three sodden hunks of flesh and fur lying in thegrass to mock me.

  He squinted his eyes against the heat shimmer rising from the river,watching Sipar hunkered beside the water's edge.

  The native rose to its feet and trotted back to him.

  "It crossed," said Sipar. "It walked out as far as it could go and itmust have swum."

  "Are you sure? It might have waded out to make us think it crossed,then doubled back again."

  He stared at the purple-green of the trees across the river. Insidethat forest, it would be hellish going.

  "We can look," said Sipar.

  "Good. You go downstream. I'll go up."

  An hour later, they were back. They had found no tracks. There seemedlittle doubt the Cytha had really crossed the river.

  They stood side by side, looking at the forest.

  "Mister, we have come far. You are brave to hunt the Cytha. You haveno fear of death."

  "The fear of death," Duncan said, "is entirely infantile. And it'sbeside the point as well. I do not intend to die."

  They waded out into the stream. The bottom shelved gradually and theyhad to swim no more than a hundred yards or so.

  They reached the forest bank and threw themselves flat to rest.

  Duncan looked back the way that they had come. To the east, theescarpment was a dark-blue smudge against the pale-blue burnished sky.And two days back of that lay the farm and the _vua_ field, but theyseemed much farther off than that. They were lost in time anddistance; they belonged to another existence and another world.

  All his life, it seemed to him, had faded and become inconsequentialand forgotten, as if this moment in his life were the only one thatcounted; as if all the minutes and the hours, all the breaths andheartbeats, wake and sleep, had pointed toward this certain hour uponthis certain stream, with the rifle molded to his hand and the cool,calculated bloodlust of a killer riding in his brain.

  * * * * *

  Sipar finally got up and began to range along the stream. Duncan satup and watched.

  Scared to death, he thought, and yet it stayed with me. At thecampfire that first night, it had said it would stick to the death andapparently it had meant exactly what it said. It's hard, he thought,to figure out these jokers, hard to know what kind of mentaloperation, what seethings of emotion, what brand of ethics and whatvariety of belief and faith go to make them and their way of life.

  It would have been so easy for Sipar to have missed the trail andswear it could not find it. Even from the start, it could have refusedto go. Yet, fearing, it had gone. Reluctant, it had trailed. Withoutany need for faithfulness and loyalty, it had been loyal and faithful.But loyal to what, Duncan wondered, to him, the outlander andintruder? Loyal to itself? Or perhaps, although that seemedimpossible, faithful to the Cytha?

  What does Sipar think of me, he asked himself, and maybe more to thepoint, what do I think of Sipar? Is there a common meeting ground? Orare we, despite our humanoid forms, condemned forever to be alien andapart?

  He held the rifle across his knees and stroked it, polishing it,petting it, making it even more closely a part of him, an instrumentof his deadliness, an expression of his determination to track andkill the Cytha.

  Just another chance, he begged. Just one second, or even less, to drawa steady bead. That is all I want, all I need, all I'll ask.

  Then he could go back across the days that he had left behind him,back to the farm and field, back into that misty other life from whichhe had been so mysteriously divorced, but which in time undoubtedlywould become real and meaningful again.

  Sipar came back. "I found the trail."

  Duncan heaved himself to his feet. "Good."

  They left the river and plunged into the forest and there the heatclosed in more mercilessly than ever--humid, stifling heat that feltlike a soggy blanket wrapped tightly round the body.

  The trail lay plain and clear. The Cytha now, it seemed, was intentupon piling up a lead without recourse to evasive tactics. Perhaps ithad reasoned that its pursuers would lose some time at the river andit may have been trying to stretch out that margin even further.Perhaps it needed that extra time, he speculated, to set up thenecessary machinery for another dirty trick.

  Sipar stopped and waited for Duncan to catch up. "Your knife, mister?"

  Duncan hesitated. "What for?"

  "I have a thorn in my foot," the native said. "I have to get it out."

  Duncan pulled the knife from his belt and tossed it. Sipar caught itdeftly.

  Looking straight at Duncan, with the flicker of a smile upon its lips,the native cut its throat.

  V

  He should go back, he knew. Without the tracker, he didn't have achance. The odds were now with the Cytha--if, indeed, they had n
otbeen with it from the very start.

  Unkillable? Unkillable because it grew in intelligence to meetemergencies? Unkillable because, pressed, it could fashion a bow andarrow, however crude? Unkillable because it had a sense of tactics,like rolling rocks at night upon its enemy? Unkillable because anative tracker would cheerfully kill itself to protect the Cytha?

  A sort of crisis-beast, perhaps? One able to develop intelligence andabilities to meet each new situation and then lapsing back to thelevel of non-intelligent contentment? That, thought Duncan, would be asensible way for anything to live. It would do away with theinconvenience and the irritability and the discontentment ofintelligence when intelligence was unneeded. But the intelligence, andthe abilities which went with it, would be there, safely tucked awaywhere one could reach in and get them, like a necklace or agun--something to be used or to be put away as the case might be.

  Duncan hunched forward and with a stick of wood pushed the firetogether.