He remembered Bikini's saying that the man who had delivered the "summons to death" to her father had looked like a mindless robot.

Mindless or not, the man bad been programmed to fight furiously and to kill.

He brought his knee up, sending Solo sprawling beyond him.

Then he stalked Napoleon, gun hefted like a club.

Solo retreated, going into a side turn off the main artery of the canyon. This seemed to be what the guard wanted. He lunged at Solo, swung the rifle, and Napoleon Solo leaped back into the darkness to safety.

He swung again and Solo backed away again. Suddenly though, instinct and the abrupt chill cry of wind warned Solo that he was being driven toward a brink.

Solo flung himself against a boulder, stayed there, timing himself. The guard swung the rifle. At the last instant Solo ducked and the rifle smashed.

Solo sprang upward, catching the guard around the knees, taking him down. They fought on the floor of the narrow gorge, rolling almost to the edge.

Solo caught his breath. The pit yawned, bottomless, narrow, a fault in the rocks. A man's body would stay there forever.

The guard's cold hands closed on Solo's throat. Solo's head hung out over the chasm.

Solo set himself, trying to lever the guard over his head. It was impossible, the silent man was possessed of superhuman strength.

Solo forgot trying to throw the man and concentrated upon staying alive.

Those hands tightened. Solo felt the canyon and the sky changing places. Red stars wheeled and skidded before him.

He swung his legs up as high as he could, caught his shoe. The fingers closed on his throat. He felt consciousness slipping away, felt his body being pressed closer to the precipice edge.

He slipped the shoe off, gripping it with all his strength. He struck the guard across the nose with it. He did it again and again.

Nothing changed. In horror he began to be afraid that the man was incapable of feeling pain. The fingers closed and he felt the last oxygen burning in his lungs.

In desperation because there was nothing else to do, Solo kept striking the guard across the nose, knowing each time he struck the blows were weaker.

Suddenly the guard whimpered, as if the battering had broken whatever mind-binding spell he was under. The hands loosened. Solo didn't delay hoping for more. Gasping in a deep, sobbing breath, he fought upward, rolling over with the guard, pulling himself back to safety.

The guard went on fighting, striking, choking, pounding. But there was a difference and Solo felt it. Now he was fighting an ordinary man of ordinary strength, no longer driven by some outside will.

Solo's fist caught the guard on the jaw. The guard slumped, then grabbed Solo's body, rolling with him toward the side of the bottomless chasm.

Solo fought wildly, realizing that the guard had been programed to kill, even if he died, too. This much remained to drive him.

Solo caught at the jutting rocks, fighting free of the guard's grasp. He thrust the heel of his hand against the man's jaw and thrust with all his strength.

The guard loosened his grip on Solo, gasping. Then Solo thrust out one more time and the guard fell away, slipping in terrible slow motion over the side of the cliff. His fingers grasped at jutting rocks, held.

Solo sank for a moment against the mountain wall, panting. He took up his shoe, stared at the man's hands gripping those rocks. Then he slipped the shoe on his foot and stood up. He exhaled heavily, speaking over the side of the cliff, "You will hang on, won't you?"

He ran around the curve in the canyon.

SIX

BIKINI WAS crouched in the shadows where he'd left her. In the light from the guard's cap he read the terror in her face. He wondered if she began to see just some of the peril into which she'd walked.

Her lips parted and she almost cried out her shock and relief at the sight of him.

He shook his head, warning her against speaking. She nodded and reached out her hand to him. Her fingers were icy.

He nodded, motioning her to follow him again. One thing he was sure of, even the lab radar would show only two of them. It was unlikely that it could reveal their identity. Two guards had come running out. Two people were returning. Perhaps they had bought a few moments of safety.

He decided to use it to the best advantage. Holding Bikini's hand tightly, he ran along the narrow gorge between the high dark canyon walls.

Suddenly the illumination was like the sun at noon. Solo paused at the turn in the rocks. Leaving Bikini pressed into the darkness, he inched forward, peered around the corner.

He caught his breath. He had seen this lab on the long-range scanner, but he'd had no idea of its immensity or complexity.

The floor of the canyon widened abruptly to a width of a hundred yards around this turn. Hundreds of feet above, the crest of the mountains closed to a few inches.

In this gorge the laboratory had been set up, and everything depended on its own artificial lighting and heating. A green haze seemed to envelope the glass walled building, but only because everywhere strange tropical plants grew lush and deeply green under this strange light. A kind of buffalo grass had sprouted wild on the bare canyon flooring under this light, growing almost to the narrowing turn.

Eyes distended, Solo remained an instant too long staring across the open space toward that glass-walled lab.

A sudden hissing alerted him. The sound ripped through the incessant buzzing which had almost become a part of the charged atmosphere.

Solo fell back behind the rock. A sharp beam of light whipped across the mouth of the open space.

Shocked, Napoleon Solo saw the buffalo grass burned gray where the beam touched it.

He stayed there for some moments, while his heart slowed to a regular beating again. Three more times the light beam reached for him, and barely missed.

He inched his way back to Bikini. She stared up at him questioningly.

Solo gazed down at Bikini for a moment, almost regretfully. She whispered. "What's the matter?"

He didn't answer. He reached out his left hand, tilting her chin slightly. Then he struck her sharply with his right, on the side of her jaw.

She slumped forward and he caught her gently.

Carrying her in his arms, he found a small break in the wall. He laid her down in the darkness, whispering, "You'll be safe here, Beautiful. Safer anyhow. Sweet dreams."

He ran back to the mouth of the canyon sump. The light beam still hissed, tilted now, no longer touching the grass as it swung out, reaching for him.

From his pack be took the small canister and sprayed it from his legs upward, covering his body with a fine mist. As he worked, the haze hardened into a flexible plastic.

After a few moments the plastic was like suiting which encased his entire body.

He waited a few seconds longer, watching that beam whip across the open. When the light passed, he stepped boldly out and ran across the opening toward the lab. The plastic was unwieldy but was flexible enough to permit movement.

Solo was within fifty feet of the lab doors when the beam raked across him.

The plastic melted and ran like teardrops. But he was only barely aware of it.

Solo staggered.

His mind fogged over. The green lights dimmed, seeming to recede into a darker canyon.

He felt as if an invisible fist struck him in the chest, barring his way, but not really hurting because it was as though he were numb.

He tried to stride forward, but his legs no longer obeyed commands from his mind.

He slumped to the ground, hearing the buzzing and the hissing louder than ever.

Gradually the green lights brightened and Napoleon Solo opened his eyes.