but like most everyone who is young, I had a genuine love for intrigue and mystery, even though they might be dangerous things to meddle with.

"Hekalu came to Taboor, but I saw comparatively little of him. He seemed always to be tremendously busy. Sometimes he would be extravagantly jubilant, as though he had met with some tremendous success, or again he would apparently be worried almost to the point of madness. What these emotional changes meant, he would never tell me.

"Several times old Alka, his favorite slave, spoke to me. 'The Master is not as he used to be, Miss Darell,' he would say. 'He works feverishly with odd mechanisms, and every night when he is at home he stares out into space toward the farther planets with his new super-telescope. Always, what he sees makes his face turn white and hard; sometimes, he smiles and sometimes his features look like a devil's mask.'

"And still Hekki's weird treasures continued, and still continue to come from the Taraal.

"A group of men was sent by the heads of the Place of Knowledge out into the desert to investigate. They disappeared. The officials of the Planetary Patrol made only a hasty and unsuccessful investigation.

"On the day of my departure from Mars, after having finished my course, I saw Hekki, believing that it was for the last time. He said he was going back into the Taraal. And then he popped up on the liner. And that, Austin, is all I know about Hekalu Selba. What do you make of it? What is he trying to do out there in the desert?" She placed her hand lightly on Shelby's arm and looked up appealingly into his face. "Can't you offer some suggestions, Austin? You know that when suspicious events are troubling you, a plausible explanation eases your mind even though you cannot know the truth. And I am afraid, afraid that he is deliberately following me to Earth!"

While Jan had been telling of her acquaintance with the Martian, Austin had been staring at a very large Sadu moth which hovered, and leisurely moved about on thrumming gorgeous wings, which spanned fully eighteen inches. It moved from blossom to blossom in a nearby flower bed, delicately sipping nectar. Always its great luminous eyes, which glowed like coals of gleaming fire, were turned toward the pair. Shelby had scarcely noticed it, for he was absorbed with the girl's account; but now, when it edged closer towards them, and then made a sudden mischievous swoop not six inches above their heads, its presence could no longer be ignored. The girl gave an exclamation of revulsion and shrank involuntarily toward her companion. He leaped to his feet, and picking up a pebble from beside the fountain, hurled it at the night prowler.

"You dirty eavesdropper!" he shouted angrily. "The man who brought your kind from Mars for ornamental purposes must have been crazy!"

The moth buzzed up into the cypress tree and squatted there, silently, apparently resting. Only its eyes continued to glare fixedly, almost malignantly at the occupants of the garden. But they quickly forgot about its presence.

"I don't know whether I can offer a sensible explanation for Hekalu's actions or not, Jan," Shelby said. "However, as far as his activities in the Taraal are concerned, it seems quite possible that he did discover ruins there, and is trying to keep other fortune seekers away. The ruins may of course not really belong to the Melbar dynasty. They might have been built by some contemporary race. Just what he is doing among the minor planets, we can't any more than guess at. Probably he's just adventuring like a few other people. And as for his following you to Earth—well, I admit that you do seem to be popular!"

"You're making it sound awfully simple, Austin," said Jan. She paused and thought for a moment, and then, with seeming irrelevance she continued: "Haven't you heard of queer clusters of luminous specks recently seen by astronomers not far beyond Mars? They called them meteor clusters, but they drifted about here and there, not following definite paths as meteors should do."

"You're trying to suggest that they are space ships, aren't you, Jan?"

She nodded.

"But they aren't," Shelby assured her. "They don't polarize the reflected light of the sun as space ships do. Besides, where could they have been built? Certainly not among the planetoids. And any place on the planets, the Taraal desert for instance, would be an almost equally impossible site for their construction.

"Think of the enormous crews of men and the vast supplies of food and water and materials that would have to be taken out there into the wilderness. Undoubtedly Hekalu could back such a project financially, but he would be discovered before he had made a fair start, and the Martian Planet Patrol would wipe him out of existence. Still, though I don't think that the luminous specks are man-built vessels, I am equally certain that they aren't meteors either."

"Then what are they?"

The young man smiled and shrugged. "I don't know," he said. The intuitive feeling that unknown, and not too beneficient forces were at work in the ether about, was troubling him again, making his scalp muscles tingle.

For a moment Shelby stared at the ground. "Jan," he said, "I didn't tell you what I saw on the liner. I didn't tell anyone because I don't want to be called a lunatic. But I guess it's all right to let you in on this now. Briefly, during the sleep period, I came upon Hekalu Selba prowling in a passageway aboard the Ekova, in the company of a vague thing that may have been similar to that shape in the photograph—long arms, big head, squat and muscular. If we knew what that thing was, and where it came from, the snarl might be half untangled."

Janice Darell's face took on a sudden surprised look. "You actually saw what you say you saw?" she cried. When her companion nodded, she continued excitedly with wide-open eyes. "I still believe that Hekalu knows something about the meteor cluster. And the beast figures in somewhere too. Austin," she cried, "what if Hekki is trying something really great? I know you don't take stock in any such idea, but just supposing he is—what if—"

"Let him try!" the young man cut in. "I almost wish he would! I'm afraid he would get the surprise of his life." He was staring straight at the unwinking, malignant eyes of the Sadu moth.

"What do you mean?"

Shelby drew a small black case from his sleeve pocket and opened it. He took from it a device which looked like a tiny pistol. There were several other odds and ends of mechanisms in the case. "For a year I have been working on a new weapon," he said. "All the parts are completed, and tonight I shall finish assembling them. This little gun is the projector for a new ray which I have discovered—an etheric vibration of extremely short wavelength. A portion of the atomic energy in any solid or liquid substance the ray touches is instantly released.

"You doubt whether it is effective? Well, I can't give you any proof now; I can only say that when I was back on Mars, fooling with my first cumbersome projector, which produced only the weakest of vibrations, I blasted a big hole in the wall of my apartment, and nearly killed the Martian physician who lived in the rooms next to mine. I had a devil of a time explaining the explosion, and narrowly missed getting myself into serious trouble. In a few days I shall try to sell the weapon to the Earth Government. If they are convinced of its value, and I don't see how they can help but be convinced, our friend from the Red Planet will have to be very careful if he tries anything."

Shelby glanced at his wrist watch. "Eleven thirty—my bed time," he said with mock seriousness. "But Jan, there's one favor I want to ask you before I go. Try not to see anymore of Hekalu Selba, Akar."

Janice Darell made a valiant attempt to act the part of one whose pride and sense of freedom had been deeply outraged. "Mr. Shelby," she said, "what right have you to tell me what I shall or shall