"Well, Digger, I can see now how these ships were brought in here; that robot could move any one of these with ease. But that doesn't explain where the humans have gone. It might be space pirates using this asteroid for a base, or it might be some alien form of life. We're still free. Shall we beat it or stay and try to check this out?"

He did not know how much of this got over to the spacehound, but the impressions he received in answer were those of approving their remaining where they were.

"I suppose the best system is to explore the rest of the caves in order; let's go."

Followed by Digger, he walked quietly toward the next cave on the left, slipped through the doorway, and, standing with his back against the wall, swung the light of his torch in a wide, swift arc about the room. Halfway around, he stopped abruptly; a slim, petite figure appeared clearly in the searchlight's glare. The girl he had seen on the televisor stood in the middle of the room, facing a telecaster, her back toward him. She did not seem aware of him as he moved forward. What could be wrong; surely that light would arouse her.

The figure did not turn as he approached. So near was he now that he could seize her easily, still she made no move. Nat stepped to one side, flashed his torch in her face. Her beautifully-lashed eyes stared straight ahead unblinkingly; the expression on her lovely composed face did not change. A robot! He laughed bitterly. But then, he was not the only one....

She was an earth product; Nat opened her helmet and found the trade-mark of Spurgin's Robots hung like a necklace about her throat. But whoever had lured him here easily could have removed her from one of the vessels in the front cave. It did not seem like the work of pirates, more likely unknown intelligent beings.

He turned to examine the televisor. It, too, was an earth product. The mechanism was of old design; evidently it had been taken from the first of the ships to land here. Outside of the telecaster and the solitary robot, there was nothing to be seen in this cave.

A sound behind him. He whirled, heat-rod poised for swift, stabbing action. Nothing—except—small bowling-ball things rolling in through a narrow door. Ridiculous things of the same yellowish-quartz material as composed the cave-walls. At regular intervals a dull, bluish light poured forth from rounded holes in their smooth sides. And issuing forth from within these comic globes was the same weird, compelling music he had heard before. They rolled up to him, brushed against his toes; a shrilling in his brain told him that Digger was aware of them.

"Back, Digger!" he thought as he drew away from the globes. They poured their penetrating blue light over him, inspectingly, while the music from within rose and fell in regular cadences, sweetly impelling and dulling to the senses as strong oriental incense.

But Digger was not soothed. The spacehound lunged at one of the globes; instead of slashing its sides, he found himself sailing through the air toward it. Nat received impressions of irritation combined with astonishment. Within the globes, the music rose to a furious whine while one of the things shot forth long tentacles from the holes in its side. Lightning-swift they shot forth, wrapped themselves about the body of the spacehound, constricting. Digger writhed vainly, his claws powerless to tear at the whip-like tentacles. Nat severed the tentacles at their base with the heat-beam.