CLOSE TO CRITICAL

slender giant's comment, but from then on watched the axes which flashed in the firelight. These really did seem to be working their way toward the huts which rimmed the top of the hill. Some failed to make it; more than one of the tools which had so suddenly become weapons ceased to swing as the robot's eyes watched.

But some did get there. For half a minute a four-armed, scaly figure stood at one of the hut doors, facing outward and smashing the crests of all attackers who approached too close. Three others, all apparently injured, crawled toward him and under the sweep of the powerful arms to take shelter in the building; one of these remained in the doorway, crouching with two spears and guarding the axeman from low thrusts.

Then another defender battered his way to the side of the first, and the two retreated together inside the hut. None of the cave-dwellers seemed eager to follow.

"Are you all inside, Nick?" Raeker asked.

"Five of us are here. I don't know about the others. I'm pretty sure Alice and Tom are dead, though; they were near me at the beginning, and I haven't seen them for some time."

"Give a call to those who aren't with you. I'll have to do something very soon, and I don't want any of you hurt by it."

"They must either be safe or dead. The fighting has stopped; it's a lot easier to hear you than it was. You'd better do whatever it is without worrying about us; I think Swift's people are all heading toward you. Only a couple are outside the door here; the others are forming a big ring around where I saw you last. You haven't moved, have you?"

"No," admitted Raeker, "and you're right about the ring. One of the biggest of them is walking right up to me. Make sure you are all under cover—preferably somewhere where light won't reach you. I'll give ten seconds."

Explanation; Concatenation; Recrimination 33

"All right," Nick answered. "We're getting under tables."

Raeker counted a slow ten, watching Hie approaching creatures in the screens as he did so. At the last number his fingers tripped a gang bar which closed twenty switches simultaneously; and as Nick described it later, "the world took fire."

It was only the robot's spotlights, unused now for years but still serviceable. It seemed quite impossible to the human watchers that any optical organs sensitive enough to work on the few quanta of light which reach the bottom of Tenebra's atmosphere could possible stand any such radiance; the lights themselves had been designed with the possibility hi mind that they might have to pierce dust or smoke—they were far more powerful'than were really needed by the receptors of the robot itself.

The attackers should have been blinded instantly, according to Raeker's figuring. The sad fact slowly emerged 4hat they were not.

They were certainly surprised. They stopped their advance for a moment, and chattered noisily among themselves; then the giant who was in front of the others strode right up to the robot, bent over, and appeared to examine one of the lights in detail. The men had long ago learned that the Tenebran vision organs were involved in some way with the spiny crests on their heads, and it was this part that the being who Raeker suspected must be Swift brought close to one of the tiny ports from which the flood of light was escaping.

The man sighed and shut off the lights.

"Nick," he called, "I'm afraid my idea didn't work. Can you get in touch with this Swift fellow, and try to get the language problem across to him? He may be trying to talk to me now, for all I can tell."

"I'll try." Nick's voice came faintly through the robot's instruments; then there was nothing but an incomprehensible chattering that ran fantastically up and down the 34