I heard a grating sound, realized that I had been grinding my teeth together in a rictus of shock. Cold sweat trickled down the side of my neck under the suit.

Down below, the creature worked busily, its gaunt, narrow-shouldered body screening its task. It shifted position, presenting its back now, the long curve of its horse-like neck.

I had to force my hand to move. I slipped the dartgun from its fitted pocket, flipped off the safety. The beast labored on, absorbed in its victim. Quick motions of its elbows reflected its deft manipulations.

A feeling of nightmarish unreality seemed to hang over the scene: the wink and rumble of the artillery beyond the hills, the knife-like sharpness of the shadows thrown by the light of the command car, the intent, demonic figure. I took careful aim just below a triangular clasp securing two straps that crossed the arched back, and fired.

The creature twitched a patch of hide impatiently, went on with its work. I aimed again, then lowered the gun without firing a second time; if one jolt of Felix's venom had no effect, two wouldn't help. I flattened myself in the pocket of shadow against the cliff-face, watched as the alien rose to a grotesque two-legged stance, then pranced away on its rear hands toward the body of the driver, lying crumpled beside the Bolo.

The major lay on his back now, the cap nearby, his gun a yard away. There was blood on his face and on the dusty stone under him. I estimated the distance to the command car, gauging the possibility of reaching it and training the forward battery on the monstrosity now leaning over the second man There was a sudden, sharp yelp. The alien darted a few steps, collided glancingly with the massive skirt of the Bolo, veered toward me. I caught a glimpse of a gaping mouth, a ragged, black tongue, teeth like needles of yellow bone.

The stricken demon bit at its rear quarters, running in a tight circle like a dog chasing its tail, yelping sharply; then it was down, kicking, scrabbling with its pale, flat hands, raising a roil of dust. Then it stiffened and lay still.

I dropped quickly to the ground, switched off the lift-field. I caught the reek of exhaust fumes, the hot-stone odor of the desert, and a sharp, sour smell that I knew came from the dead creature.

I went to the body of the major and bent over it. The face was slack, the eyelids unnaturally sunken. There was a clean wound across the forehead at the hairline. The hair was matted with glistening blood.

I turned him on his face. The top of his skull had been cut free; it hung in place on a hinge of scalp. Inside the glistening red-black cavity was-nothing.

I leaned closer. A deep incision gaped from the base of the skull down under the collar. Very little blood had leaked from it; the heart had stopped before the wound was made.

The alien lay fifteen feet away. I looked across at it, my breathing coming fast and shallow, hissing between teeth that were bared in a snarl. Every instinct I owned was telling me to put space between myself and the demonic creature that had walked like a beast but had used its hands like a man.

I had heard of hackles rising; now I felt them. I gripped the gun tighter as I crossed the last few feet, stood looking down at the sparse, rumpled coat through which dull gray-pink skin showed. I prodded the body with a boot; it was stiff, inert, abnormally heavy. I pushed harder, rolled it over. At close range, the face was yellowish white, dry, porous-textured. The hands were outflung, palms up, bloody from the trepanning of the major; near one lay a bulging, gallon-sized sack, opaque with dust.

I stepped around to it, knelt and wiped a finger across the bulge of the surface; it was yielding, warm to the touch. Pinkish fluid wobbled under the taut membrane.

I brushed away more dust. Now I could see a pink, jelly-like mass suspended in the liquid. It had a furrowed surface, like sun-baked mud, and from its underside hung a thick, curled stem, neatly snipped off three inches down.

I prodded the bag. The mass stirred; a snow-white sphere just smaller than a golf ball wavered into view, turning to show me a ring of amber-brown with a black center dot.

The battle sounds were slackening now. It wouldn't be long before another vehicle came along the ravine in search of the missing Bolo and the officer who had followed it. I stood, feeling my heart pound as though I had run a mile, fighting down the sickish feeling that knotted my stomach. I didn't have much time, and there were things to be done-now.

The tankman, lying awkwardly beside his massive machine, was dead, already cooling to the touch. I went back to the fallen demon, went through the pouches attached to the creature's harness, and found a case fitted with scalpels, forceps, a tiny saber saw. There was a supply of plastic containers and a miniature apparatus with attached tubing-probably a pump-and-filter combination for drawing off plasma. There was another container, packed with ampoules of a design I had seen recently-on the landing in my hotel. The thought was like a cold finger on my spine.

The last pouch yielded a scrap of smooth, tough paper, imprinted with lines of pot-hooks of a sort I had never seen before. I tucked it away in my knee-pocket, got to my feet. The paper was better than nothing as evidence that I hadn't been the dreamer of a particularly horrible nightmare. But I needed something more compelling-something that would communicate some of the shock I felt. Felix needed to see that skull-white face…

The ravine was still quiet; maybe I had time.

I ran to the car, started it up and brought it forward, halted it beside the dead man. I jumped down and lifted the limp body into the cockpit. I remounted, maneuvered up beside the dead alien. I opened the cargo compartment at the rear of the car, then gritted my teeth and grasped the creature's hind wrists. Through the gloved hands of the suit, the bristles were as stiff as scrub-brushes.

I dragged the corpse to the car, used the power of the suit to lift the three-hundred-pound weight, and tumbled it inside.

I went back for the sack containing the brain, put it on the seat beside the dead major, then climbed in and headed back up the ravine. As I reached the first turn, a glare of light projected the car's moving shadow on the rock wall ahead. I turned, saw a brilliant flare fountain from the open hatch of the Bolo.

I gunned the car, and felt a tremor run through the rock an instant before I heard the blast. Small stones rained down, bounded off the canopy and hood. Either the tank had been mined for automatic destruction if abandoned or else the creature I had killed had set a time-charge to eliminate the traces of his visit.

I tramped on the throttle, holding my thoughts rigidly on my driving. I wasn't ready yet to think about the implications of what I had seen. I could feel the full shock of it, lurking in the wings, waiting to jump out and send me screaming for a policeman-but that would have to wait. Now, I was concerned only with getting clear with my prize while there was still time.

Because there was no doubt that in a little while-when whoever, or whatever, was awaiting the return of the brain-thief realized that something was awry-a variety of hell would break loose that would make ordinary death and destruction seem as mild and wholesome as a spring morning.

I skirted the hills where floodlights were glaring now in the Moroccan camp. The cease-fire had apparently been sounded; UN monitors would be moving out on the field, tallying casualties, looking for evidence of illegal weapons, checking out complaints by both sides of Battle Plan violations. I hoped that in the general excitement the absence of the command car would go unnoticed for now. The road into Tamboula was a wide, well-patrolled highway. I avoided it, took a route across a wasteland of stunted mesquite. I skirted a trenched and irrigated field, orderly in the light of the new-risen moon, then stopped by a clump of trees fifty yards from Felix's villa, a former farmhouse, converted by the CBI into an armored fortress capable of withstanding a siege that would have leveled Stalingrad. The windows were dark. I took out my communicator, pressed the red button that tuned it to Felix's special equipment.