"Well, so long, mate," he grunted, and spun around and dug his toes in the sand and was away. I stood there staring at his rapidly disappearing form for a few moments and then looked back once more at the house. A tattered cotton curtain was just swinging to in the dirty, sand-blown window. That seemed to mean the woman had been watching. I sighed, shrugged again and went away myself.

When I got back to Security Headquarters, I went to the file and began to rifle through pictures. I didn't find the woman, but I did find the man.

He was a killer named Harry Smythe.

I took the picture into the Chief's office and laid it on his desk, waited for him to look down at it and study it for an instant, and then to look back up to me. Which he did.

"So?" he said.

"Wanted, isn't he?"

He nodded. "But a lot of good that'll do. He's holed up somewhere back on Earth."

"No," I said. "He's right here. I just saw him."

"What?" He nearly leaped out of his chair.

"I didn't know who he was at first," I said. "It wasn't until I looked in the files—"

He cut me off. His hand darted into his desk drawer and pulled out an Authority Card. He shoved the card at me. He growled: "Kill or capture, I'm not especially fussy which. Just get him!"

I nodded and took the card. As I left the office, I was thinking of something which struck me as somewhat more than odd.

I had idly listened to a little half-breed Martian boy whistling part of the William Tell Overture, and it had led me to a wanted killer named Harry Smythe.

Understandably, Mr. Smythe did not produce himself on a silver platter. I spent the remainder of the afternoon trying to get a lead on him and got nowhere. If he was hiding in any of the places I went to, then he was doing it with mirrors, for on Mars an Authority Card is the big stick than which there is no bigger. Not solely is it a warrant, it is a commandeer of help from anyone to whom it is presented; and wherever I showed it I got respect.

I got instant attention. I got even more: those wraithlike tremblings in the darker corners of saloons, those corners where light never seems quite to penetrate. You don't look into those. Not if you're anything more than a ghoul, you don't.

Not finding him wasn't especially alarming. What was alarming, though, was not finding the Earthwoman and her little half-breed Martian son when I went back to the tumbledown shack where they lived. It was empty. She had moved fast. She hadn't even left me a note saying good-by.

That night I went into the Great Northern desert to the Haremheb Reservation, where the Martians still try to act like Martians.

It was Festival night, and when I got there they were doing the dance to the two moons. At times like this you want to leave the Martians alone. With that thought in mind, I pinned my Authority Card to my lapel directly above my badge, and went through the gates.

The huge circle fire was burning and the dance was in progress. Briefly, this can be described as something like the ceremonial dances put on centuries ago by the ancient aborigines of North America. There was one important exception, however. Instead of a central fire, the Martians dig a huge circular trench and fill it with dried roots of the belu tree and set fire to it. Being pitch-like, the gnarled fragments burn for hours. Inside this ring sit the spectators, and in the exact center are the dancers. For music, they use the drums.

The dancers were both men and women and they were as naked as Martians can get, but their dance was a thing of grace and loveliness. For an instant—before anyone observed me—I stood motionless and watched the sinuously undulating movements, and I thought, as I have often thought before, that this is the one thing the Martians can still do beautifully. Which, in a sad sort of way, is a commentary on the way things have gone since the first rocket-blasting ship set down on these purple sands.

I felt the knife dig my spine. Carefully I turned around and pointed my index finger to my badge and card. Bared teeth glittered at me in the flickering light, and then the knife disappeared as quickly as it had come.

"Wahanhk," I said. "The Chief. Take me to him."

The Martian turned, went away from the half-light of the circle. He led me some yards off to the north to a swooping-tent. Then he stopped, pointed.

"Wahanhk," he said.

I watched him slip away.

Wahanhk is an old Martian. I don't think any Martian before him has ever lived so long—and doubtless none after him will, either. His leathery, almost purple-black skin was rough and had a charred look about it, and up around the eyes were little plaits and folds that had the appearance of being done deliberately by a Martian sand-artist.

"Good evening," I said, and sat down before him and crossed my legs.

He nodded slowly. His old eyes went to my badge.

From there they went to the Authority Card.

"Power sign of the Earthmen," he muttered.

"Not necessarily," I said. "I'm not here for trouble. I know as well as you do that, before tonight is finished, more than half of your men and women will be drunk on illegal whiskey."

He didn't reply to that.

"And I don't give a damn about it," I added distinctly.

His eyes came deliberately up to mine and stopped there. He said nothing. He waited. Outside, the drums throbbed, slowly at first, then moderated in tempo. It was like the throbbing—or sobbing, if you prefer—of the old, old pumps whose shafts go so tirelessly down into the planet for such pitifully thin streams of water.

"I'm looking for an Earthwoman," I said. "This particular Earthwoman took a Martian for a husband."

"That is impossible," he grunted bitterly.

"I would have said so, too," I agreed. "Until this afternoon, that is."

His old, dried lips began to purse and wrinkle.

"I met her little son," I went on. "A little semi-human boy with Martian features. Or, if you want to turn it around and look at the other side, a little Martian boy who whistles."

His teeth went together with a snap.

I nodded and smiled. "You know who I'm talking about."

For a long long while he didn't answer. His eyes remained unblinking on mine and if, earlier in the day, I had thought the little boy's face was expressionless, then I didn't completely appreciate the meaning of that word. Wahanhk's face was more than expressionless; it was simply blank.

"They disappeared from the shack they were living in," I said. "They went in a hurry—a very great hurry."

That one he didn't answer, either.

"I would like to know where she is."

"Why?" His whisper was brittle.

"She's not in trouble," I told him quickly. "She's not wanted. Nor her child, either. It's just that I have to talk to her."

"Why?"

I pulled out the file photo of Harry Smythe and handed it across to him. His wrinkled hand took it, pinched it, held it up close to a lamp hanging from one of the ridge poles. His eyes squinted at it for a long moment before he handed it back.

"I have never seen this Earthman," he said.

"All right," I answered. "There wasn't anything that made me think you had. The point is that he knows the woman. It follows, naturally, that she might know him."

"This one is wanted?" His old, broken tones went up slightly on the last word.

I nodded. "For murder."

"Murder." He spat the word. "But not for the murder of a Martian, eh? Martians are not that important any more." His old eyes hated me with an intensity I didn't relish.

"You said that, old man, not I."

A little time went by. The drums began to beat faster. They were rolling out a lively tempo now, a tempo you could put music to.

He said at last: "I do not know where the woman is. Nor the child."

He looked me straight in the eyes when he said it—and almost before the words were out of his mouth, they were whipped in again on a drawn-back, great, sucking breath. For, somewhere outside, somewhere near that dancing circle, in perfect time with the lively beat of the drums, somebody was whistling.

It was a clear, clean sound, a merry, bright, happy sound, as sharp and as precise as the thrust of a razor through a piece of soft yellow cheese.

"In your teeth, Wahanhk! Right in your teeth!"

He only looked at me for another dull instant and then his eyes slowly closed and his hands folded together in his lap. Being caught in a lie only bores a Martian.

I got up and went out of the tent.

The woman never heard me approach. Her eyes were toward the flaming circle and the dancers within, and, too, I suppose, to her small son who was somewhere in that circle with them, whistling. She leaned against the bole of a belu tree with her arms down and slightly curled backward around it.

"That's considered bad luck," I said.

Her head jerked around with my words, reflected flames from the circle fire still flickering in her eyes.

"That's a belu tree," I said. "Embracing it like that is like looking for a ladder to walk under. Or didn't you know?"

"Would it make any difference?" She spoke softly, but the words came to me above the drums and the shouts of the dancers. "How much bad luck can you have in one lifetime, anyway?"

I ignored that. "Why did you pull out of that shack? I told you you had nothing to fear from me."

She didn't answer.

"I'm looking for the man you saw me talking with this morning," I went on. "Lady, he's wanted. And this thing, on my lapel is an Authority Card. Assuming you know what it means, I'm asking you where he is."

"What man?" Her words were flat.

"His name is Harry Smythe."

If that meant anything to her, I couldn't tell. In the flickering light from the fires, subtle changes in expression weren't easily detected.

"Why should I care about an Earthman? My husband was a Martian. And he's dead, see? Dead. Just a Martian. Not fit for anything, like all Martians. Just a bum who fell in love with an Earthwoman and had the guts to marry her. Do you understand? So somebody murdered him for it. Ain't that pretty? Ain't that something to make you throw back your head and be proud about? Well, ain't it? And let me tell you, Mister, whoever it was, I'll get him. I'll get him!"

I could see her face now, all right. It was a twisted, tortured thing that writhed at me in its agony. It was small yellow teeth that bared at me in viciousness. It was eyes that brimmed with boiling, bubbling hate like a ladle of molten steel splashing down on bare, white flesh. Or, simply, it was the face of a woman who wanted to kill the killer of her man.

And then, suddenly, it wasn't. Even though the noise of the dance and the dancers was loud enough to command the attention and the senses. I could still hear her quiet sobbing, and I could see the heaving of the small, thin shoulders.

And I knew then the reason for old Wahanhk's bitterness when he had said to me, "But not for the murder of a Martian, eh? Martians are not that important any more."

What I said then probably sounded as weak as it really was: "I'm sorry, kid. But look, just staking out in that old shack of yours and trying to pry information out of the type of men who drifted your way—well, I mean there wasn't much sense in that, now was there?"

I put an arm around her shoulders. "He must have been a pretty nice guy," I said. "I don't think you'd have married him if he wasn't."

I stopped. Even in my own ears, my words sounded comfortless. I looked up, over at the flaming circle and at the sweat-laved dancers within it. The sound of the drums was a wild cacophonous tattoo now, a rattle of speed and savagery combined; and those who moved to its frenetic jabberings were not dancers any more, but only frenzied, jerking figurines on the strings of a puppeteer gone mad.

I looked down again at the woman. "Your little boy and his butterfly net," I said softly. "In a season when no butterflies can be found. What was that for? Was he part of the plan, too, and the net just the alibi that gave him a passport to wander where he chose? So that he could listen, pick up a little information here, a little there?"

She didn't answer. She didn't have to answer. My guesses can be as good as anybody's.

After a long while she looked up into my eyes. "His name was Tahily," she said. "He had the secret. He knew where the gold vein was. And soon, in a couple of years maybe, when all the prospectors were gone and he knew it would be safe, he was going to stake a claim and go after it. For us. For the three of us."

I sighed. There wasn't, isn't, never will be any gold on this planet. But who in the name of God could have the heart to ruin a dream like that?

Next day I followed the little boy. He left the reservation in a cheery frame of mind, his whistle sounding loud and clear on the thin morning air. He didn't go in the direction of town, but the other way—toward the ruins of the ancient Temple City of the Moons. I watched his chubby arm and the swinging of the big butterfly net on the end of that arm. Then I followed along in his sandy tracks.

It was desert country, of course. There wasn't any chance of tailing him without his knowledge and I knew it. I also knew that before long he'd know it, too. And he did—but he didn't let me know he did until we came to the rag-cliffs, those filigree walls of stone that hide the entrance to the valley of the two moons.

Once there, he paused and placed his butterfly net on a rock ledge and then calmly sat down and took off his shoes to dump the sand while he waited for me.

"Well," I said. "Good morning."

He looked up at me. He nodded politely. Then he put on his shoes again and got to his feet.

"You've been following me," he said, and his brown eyes stared accusingly into mine.

"I have?"

"That isn't an honorable thing to do," he said very gravely. "A gentleman doesn't do that to another gentleman."

I didn't smile. "And what would you have me do about it?"

"Stop following me, of course, sir."

"Very well," I said. "I won't follow you any more. Will that be satisfactory?"

"Quite, sir."

Without another word, he picked up his butterfly net and disappeared along a path that led through a rock crevice. Only then did I allow myself to grin. It was a sad and pitying and affectionate kind of grin.

I sat down and did with my shoes as he had done. There wasn't any hurry; I knew where he was going. There could only be one place, of course—the city of Deimos and Phobos. Other than that he had no choice. And I thought I knew the reason for his going.

Several times in the past, there have been men who, bitten with the fever of an idea that somewhere on this red planet there must be gold, have done prospecting among the ruins of the old temples. He had probably heard that there were men there now, and he was carrying out with the thoroughness of his precise little mind the job he had set himself of finding the killer of his daddy.

I took a short-cut over the rag-cliffs and went down a winding, sand-worn path. The temple stones stood out barren and dry-looking, like breast bones from the desiccated carcass of an animal. For a moment I stopped and stared down at the ruins. I didn't see the boy. He was somewhere down there, though, still swinging his butterfly net and, probably, still whistling.

I started up once more.

And then I heard it—a shrill blast of sound in an octave of urgency; a whistle, sure, but a warning one.

I stopped in my tracks from the shock of it. Yes, I knew from whom it had come, all right. But I didn't know why.

And then the whistle broke off short. One instant it was in the air, shrieking with a message. The next it was gone. But it left tailings, like the echo of a death cry slowly floating back over the dead body of the creature that uttered it.

I dropped behind a fragment of the rag-cliff. A shot barked out angrily. Splinters of the rock crazed the morning air.