animal, as had happened with the forest ranger.

The psychiatrists were divided in their opinions. Some thought that the call had been from a deranged person. When the Nipe actually showed up at the appointed place, those minds changed rapidly.

The Nipe's ability to use any human language was limited. He picked up vocabulary and grammatical rules very rapidly, but he seemed completely unable to use a language beyond discussion of concrete actions and objects. His mind was simply too alien to enable him to do more than touch the edges of human communication.

In the discussion of mathematics, in particular, the Nipe seemed to be completely at a loss. He apparently thought of mathematics as a spoken language instead of a written one, and could not progress beyond simple diagrams.

He wasn't captured in any real sense of the word. He refused to allow any physical tests on his body, and, short of threatening him at gun-point, there didn't seem to be any practicable way to force him to accede to the human's wishes. And they couldn't do that.

The Nipe had to be treated as an emissary from his home world, wherever that was. He'd killed a man, yes. But that had to be allowed as justifiable homicide in self-defense, since the forester had drawn a gun and was ready to fire. Nobody could blame the late Wang Kulichenko for that, but nobody could blame the Nipe, either.

For six weeks, the humans and the Nipe had tried to arrive at a meeting of minds, and just when it would seem within grasp, it would fade away into mist. It was nearly a month before the Russian psychologists and psychiatrists realized that the reason the Nipe had come to them was because he had thought that they were the ruling body of that territory!

The UN observers stayed out of it at first. Before there was any kind of talk on a Government level, there must be some kind of understanding on a personal level. And that, of course, was never achieved.

Just what had set off the Nipe's anger hasn't been established yet, as far as Stanton knew. At a meeting one day, he had simply become more and more incomprehensible, and then, without any warning, he had leaped out, killed three of the men with his bare hands, and gone out the window.

And that had been the end of any diplomatic relations between humanity and the Nipe.

Since that time, he'd been on a rampage of robbery and murder. He was as callously indifferent to human life and property as a human being might be with the life and property of a cockroach.

There have been human criminals whose actions could be described in the same way, but the Nipe had a few touches that few human criminals would have thought of and almost none would have had the capacity to execute.

If, for instance, the Nipe had time to spare, his victims would be an annoying problem in identification when found, for there would be nothing left but well-gnawed bones. And "time to spare," in this case meant twenty or thirty minutes. The Nipe had, if nothing else, a very efficient digestive tract. He ate like a shrew.

And the Nipe never, under any circumstances, used any weapon but the weapons Nature had given him—hands-or-feet, or claws or teeth. Never did he use a knife or gun or even a club.

Almost as an afterthought, one realized that the loot which the Nipe stole was seemingly unpredictable. Money, as such, he apparently had no use for. He had taken gold, silver, and platinum, but one raid for each of these elements had evidently been enough, except for silver, which had required three raids over a period of four years. Since then, he hadn't touched silver again.

He hadn't tried yet for any of the radioactives except radium. He'd taken a full ounce of that in five raids, but hadn't attempted to get his hands on uranium, thorium, plutonium, or any of the other elements normally associated with atomic energy. Nor had he tried to steal any of the fusion materials; the heavy isotopes of hydrogen or any of the lithium isotopes. Beryllium had been taken, but whether there was any significance in the thefts or not, no one knew.

There was a pattern in the thefts, nonetheless. They had begun small and increased. Scientific and technical instruments—oscilloscopes, X-ray generators, radar equipment, maser sets, dynostatic crystals, thermolight resonators, and so on—were stolen complete or gutted for various parts. After awhile, he went on to bigger things—whole aircraft, with their crews, had vanished.

That he had not committed anywhere near all the crimes that had been attributed to him was certain; that he had committed a great many of them was equally certain.

There was no doubt at all that his loot was being used to make instruments and devices of unknown kinds. He had used several of them on his raids. The one that could apparently phase out almost any electromagnetic frequency up to about a hundred thousand megacycles—including sixty-cycle power frequencies—was considered to be a particularly cute item. So was the gadget that reduced the tensile strength of concrete to about that of a good grade of marshmallow.

After he had been operating for a few years, there was no installation on the face of the earth that could be considered Nipe-proof for more than a few minutes. He struck when and where he wanted and took whatever he needed.

It was manifestly impossible to guard against the Nipe, since no one knew what sort of loot might strike his fancy next, and there was therefore no way of knowing where or how he would hit next.

Nor could he ever be found after one of his raids. They were plotted and followed out with diabolical accuracy and thoroughness. He struck, looted, and vanished. And wasn't seen again until his next strike.

Colonel Mannheim, who had carefully puffed a cigar alight and smoked it thoughtfully during Stanton's recitation, dropped the remains of the cigar into an ash receptacle. "Accurate but incomplete," he said quietly. "You must have made some guesses." He looked from Bart Stanton to Dr. Farnsworth. "I'd like to hear them."

Farnsworth finished off the last of his coffee. "We've talked about it," he admitted. "Although I must say the hypothesis Bart has come up with would never have occurred to me. I'm still not sure I credit it, but" ... he shrugged ... "I can't say that I disbelieve it, either."

Mannheim turned his eyes back to Stanton. His silence was a question.

"Logically, my theory mightn't hold much water," Stanton admitted. "But the evidence seems to be conclusive enough to me." He got up, went over to the coffee urn, and refilled his cup. "It seems incredible to me that the combined intelligence and organizational ability of the UN Government is incapable of finding anything out about one single alien, no matter how competent he may be," he said as he returned to his seat.

"Somehow, somewhere, someone must have gotten a line on the Nipe. He must have a base for his operations, and someone should have found it by this time.

"If there is such a base, then it must be possible to blast him out of it without resorting to the kind of work it took to produce—me.

"I may be faster and more sensitive and stronger than the average man, but that doesn't mean that I have superhuman abilities to the extent that I can do in two or three years what the combined forces of the Government couldn't do in ten. Certainly you wouldn't rely too heavily on it.

"And yet, apparently, you are.

"To me that can only mean that you've got another ace up your sleeve. You know we're going to get the Nipe before I die. You either have a sure way of tracing him or