Roal looked at the spot Shorty indicated. A wide, shuffled path in the sand looked as if a herd of sheep had passed that way. "Fresh, too," said Roal. "Looks as if a whole congregation of Martians had come this way recently." "Shall we follow it." "We may as well. There's a chance it leads to the burrow of Toomar. Burrows are pretty far apart, you know." The path was obvious because of its freshness, but the tracks were not deep and already the shifting sands were smoothing under the caress of the night wind. In half an hour they would be gone. All at once they vanished and the sands were smooth as a sheet. "Here it is," said Shorty. "Their hole must be right here somewhere." Roal prodded the sands with his foot. After a moment he struck the hard surface of a door over a burrow shaft. He scooped away a spot and pounded forcefully on the stone door. It echoed dully like the hollowness of a tomb. But after a moment there was a slow motion and the sand slid down as the slab rose. A withered Martian head poked cautiously above the sand as Roal and Shorty darted behind the slab. "Who comes?" the Martian whispered. "We seek Toomar," said Roal. "Toomar is below. What business have you with him?" "I was waiting on the desert a few days ago and Toomar was kind enough to offer water in his burrow. But when I emerged I found that someone below had stolen a small white gem from me. I have come to claim the gem." "We are most sorry that such an unfortunate occurrence should be laid at our door," said the Martian humbly. "Come below. I know nothing of it, but I am sure that none among us was guilty of such a crime. You may make any demands you wish in procuring the gem again. If one of us is guilty, he shall be punished." So far the Martian's acts were in accord with the habits of his race and the relationship established with Earthmen. But it seemed to Roal that he almost overdid it. The Martian was almost _anxious_ to get them into the burrow. But it was ridiculous, he told himself. He would find nothing here. And the Martian was only trying to avoid trouble. * * * * * Nevertheless, the Earthmens' hands strayed to their lances as they descended into the dark depths of the burrow. The narrow shaft was the same as the one he had previously entered, Roal was certain. A few Martians were sitting against the walls in the first chamber to which they came. The dim light came from phosphorescent stones set into the walls. Despite the air of carelessness which appeared as the Martians' perpetual guise, there was a tension that Roal could not define. It wasn't in their stick-like limbs, nor was it in their dull eyes. But it was in the very air that Roal breathed and he could not help looking about warily. In a moment the guide returned from his disappearance down a side tunnel. "Toomar comes," he announced. The Martian who had offered Roal water appeared now and surveyed them. Roal repeated the story of the theft.