“Come right in, gentlemen,” the Ambassador waved them into the very special suite the State Department had given him. “Please be seated.”

Colonel Cercy accepted a chair, trying to size up the individual who had all Washington chewing its fingernails. The Ambassador hardly looked like a menace. He was of medium height and slight build, dressed in a conservative brown tweed suit that the State Department had given him. His face was intelligent, finely molded and aloof.

As human as a human, Cercy thought, studying the alien with bleak, impersonal eyes.

“How may I serve you?” the Ambassador asked, smiling.

“The President has put me in charge of your case,” Cercy said. “I’ve studied Professor Darrig’s reports--” he nodded at the scientist beside him--”but I’d like to hear the whole thing for myself.”

“Of course,” the alien said, lighting a cigarette. He seemed genuinely pleased to be asked; which was interesting, Cercy thought. In the week since he had landed, every important scientist in the country had been at him.

But in a pinch they call the Army, Cercy reminded himself. He settled back in his chair, both hands jammed carelessly in his pockets. His right hand was resting on the butt of a .45, the safety off.

“I have come,” the alien said, “as an ambassador-at-large, representing an empire that stretches half-way across the Galaxy. I wish to extend the welcome of my people and to invite you to join our organization.”

“I see,” Cercy replied. “Some of the scientists got the impression that participation was compulsory.”

“You will join,” the Ambassador said, blowing smoke through his nostrils.

Cercy could see Darrig stiffen in his chair and bite his lip. Cercy moved the automatic to a position where he could draw it easily. “How did you find us?” he asked.

“We ambassadors-at-large are each assigned an unexplored section of space,” the alien said. “We examine each star-system in that region for planets, and each planet for intelligent life. Intelligent life is rare in the Galaxy, you know.”

Cercy nodded, although he hadn’t been aware of the fact.

“When we find such a planet, we land, as I did, and prepare the inhabitants for their part in our organization.”

“How will your people know that you have found intelligent life?” Cercy asked.

“There is a sending mechanism that is part of our structure,” the Ambassador answered. “It is triggered when we reach an inhabited planet. This signal is beamed continually into space, to an effective range of several thousand light-years. Follow-up crews are continually sweeping through the limits of the reception area of each Ambassador, listening for such messages. Detecting one, a colonizing team follows it to the planet.”

He tapped his cigarette delicately on the edge of an ash tray. “This method has definite advantages over sending combined colonization and exploration teams obviously. It avoids the necessity of equipping large forces for what may be decades of searching.”

“Sure.” Cercy’s face was expressionless. “Would you tell me more about this message?”

“There isn’t much more you need know. The beam is not detectable by your methods and, therefore, cannot be jammed. The message continues as long as I am alive.”

Darrig drew in his breath sharply, glancing at Cercy.

“If you stopped broadcasting,” Cercy said casually, “our planet would never be found.”

“Not until this section of space was resurveyed,” the diplomat agreed.

“Very well. As a duly appointed representative of the President of the United States, I ask you to stop transmitting. We don’t choose to become part of your empire.”

“I’m sorry,” the Ambassador said. He shrugged his shoulders easily. Cercy wondered how many times he had played this scene on how many other planets.

“There’s really nothing I can do.” He stood up.

“Then you won’t stop?”

“I can’t. I have no control over the sending, once it’s activated.” The diplomat turned and walked to the window. “However, I have prepared a philosophy for you. It is my duty, as your Ambassador, to ease the shock of transition as much as possible. This philosophy will make it instantly apparent that--”

As the Ambassador reached the window, Cercy’s gun was out of his pocket and roaring. He squeezed six rounds in almost a single explosion, aiming at the Ambassador’s head and back. Then an uncontrollable shudder ran through him.

The Ambassador was no longer there!

Cercy and Darrig stared at each other. Darrig muttered something about ghosts. Then, just as suddenly, the Ambassador was back.

“You didn’t think,” he said, “that it would be as easy as all that, did you? We Ambassadors have, necessarily, a certain diplomatic immunity.” He fingered one of the bullet holes in the wall. “In case you don’t understand, let me put it this way. It is not in your power to kill me. You couldn’t even understand the nature of my defense.”

He looked at them, and in that moment Cercy felt the Ambassador’s complete alienness.

“Good day, gentlemen,” he said.

Darrig and Cercy walked silently back to the control room. Neither had really expected that the Ambassador would be killed so easily, but it had still been a shock when the slugs had failed.

“I suppose you saw it all, Malley?” Cercy asked, when he reached the control room.

The thin, balding psychiatrist nodded sadly. “Got it on film, too.”

“I wonder what his philosophy is,” Darrig mused, half to himself.

“It was illogical to expect it would work. No race would send an ambassador with a message like that and expect him to live through it. Unless--”

“Unless what?”

“Unless he had a pretty effective defense,” the psychiatrist finished unhappily.

Cercy walked across the room and looked at the video panel. The Ambassador’s suite was very special. It had been hurriedly constructed two days after he had landed and delivered his message. The suite was steel and lead lined, filled with video and movie cameras, recorders, and a variety of other things.

It was the last word in elaborate death cells.

In the screen, Cercy could see the Ambassador sitting at a table. He was typing on a little portable the Government had given him.

“Hey, Harrison!” Cercy called. “Might as well go ahead with Plan Two.”

Harrison came out of a side room where he had been examining the circuits leading to the Ambassador’s suite. Methodically he checked his pressure gauges, set the controls and looked at Cercy. “Now?” he asked.

“Now.” Cercy watched the screen. The Ambassador was still typing.

Suddenly, as Harrison sent home the switch, the room was engulfed in flames. Fire blasted out of concealed holes in the walls, poured from the ceiling and floor.

In a moment, the room was like the inside of a blast furnace.

Cercy let it burn for two minutes, then motioned Harrison to cut the switch. They stared at the roasted room.

They were looking, hopefully, for a charred corpse.

But the Ambassador reappeared beside his desk, looking ruefully at the charred typewriter. He was completely unsinged.

“Could you get me another typewriter?” he asked, looking directly at one of the hidden projectors. “I’m setting down a philosophy for you ungrateful wretches.”

He seated himself in the wreckage of an armchair. In a moment, he was apparently asleep.

“All right, everyone grab a seat,” Cercy said. “Time for a council of war.”

Malley straddled a chair backward. Harrison lighted a pipe as he sat down, slowly puffing it into life.

“Now, then,” Cercy said. “The Government has dropped this squarely in our laps. We have to kill the Ambassador--obviously. I’ve been put in charge.” Cercy grinned with regret. “Probably because no one higher up wants the responsibility of failure. And I’ve selected you three as my staff. We can have anything we want, any assistance or advice we need. All right. Any ideas?”

“How about Plan Three?” Harrison asked.

“We’ll get to that,” Cercy said. “But I don’t believe it’s going to work.”

“I don’t either,” Darrig agreed. “We don’t even know the nature of his defense.”

“That’s the first order of business. Malley, take all our data so far, and get someone to feed it into the Derichman Analyzer. You know the stuff we want. What properties has X, if X can do thus and thus?”

“Right,” Malley said. He left, muttering something about the ascendancy of the physical sciences.

“Harrison,” Cercy asked, “is Plan Three set up?”

“Sure.”

“Give it a try.”

While Harrison was making his last adjustments, Cercy watched Darrig. The plump little physicist was staring thoughtfully into space, muttering to himself. Cercy hoped he would come up with something. He was expecting great things of Darrig.

Knowing the impossibility of working with great numbers of people, Cercy had picked his staff with care. Quality was what he wanted.

With that in mind, he had chosen Harrison first. The stocky, sour-faced engineer had a reputation for being able to build anything, given half an idea of how it worked.

Cercy had selected Malley, the psychiatrist, because he wasn’t sure that killing the Ambassador was going to be a purely physical problem.

Darrig was a mathematical physicist, but his restless, curious mind had come up with some interesting theories in other fields. He was the only one of the four who was really interested in the Ambassador as an intellectual problem.

“He’s like Metal Old Man,” Darrig said finally.

“What’s that?”

“Haven’t you ever heard the story of Metal Old Man? Well, he was a monster covered with black metal armor. He was met by Monster-Slayer, an Apache culture hero. Monster-Slayer, after many attempts, finally killed Metal Old Man.”

“How did he do it?”

“Shot him in the armpit. He didn’t have any armor there.”

“Fine,” Cercy grinned. “Ask our Ambassador to raise his arm.”

“All set!” Harrison called.

“Fine. Go.”

In the Ambassador’s room, an invisible spray of gamma rays silently began to flood the room with deadly radiation.

But there was no Ambassador to receive them.

“That’s enough,” Cercy said, after a while. “That would kill a herd of elephants.”

But the Ambassador stayed invisible for five hours, until some of the radioactivity had abated. Then he appeared again.

“I’m still waiting for that typewriter,” he said.

“Here’s the Analyzer’s report.” Malley handed Cercy a sheaf of papers. “This is the final formulation, boiled down.”

Cercy read it aloud: “The simplest defense against any and all weapons, is to become each particular weapon.”

“Great,” Harrison said. “What does it mean?”

“It means,” Darrig explained, “that when we attack the Ambassador with fire, he turns into fire. Shoot at him, and he turns into a bullet--until the menace is gone, and then he changes back again.” He took the papers out of Cercy’s hand and riffled through them.

“Hmm. Wonder if there’s any historical parallel? Don’t suppose so.” He raised his head. “Although this isn’t conclusive, it seems logical enough. Any other defense would involve recognition of the weapon first, then an appraisal, then a countermove predicated on the potentialities of the weapon. The Ambassador’s defense would be a lot faster and safer. He wouldn’t have to recognize the weapon. I suppose his body simply identifies, in some way, with the menace at hand.”

“Did the Analyzer say there was any way of breaking this defense?” Cercy asked.

“The Analyzer stated definitely that there was no way, if the premise were true,” Malley answered gloomily.

“We can discard that judgment,” Darrig said. “The machine is limited.”

“But we still haven’t got any way of stopping him,” Malley pointed out. “And he’s still broadcasting that beam.”

Cercy thought for a moment. “Call in every expert you can find. We’re going to throw the book at the Ambassador. I know,” he said, looking at Darrig’s dubious expression, “but we have to try.”

During the next few days, every combination and permutation of death was thrown at the Ambassador. He was showered with weapons, ranging from Stone-Age axes to modern high-powered rifles, peppered with hand grenades, drowned in acid, suffocated in poison gas.

He kept shrugging his shoulders philosophically, and continued to work on the new typewriter they had given him.

Bacteria was piped in, first the known germ diseases, then mutated species.

The diplomat didn’t even sneeze.

He was showered with electricity, radiation, wooden weapons, iron weapons, copper weapons, brass weapons, uranium weapons--anything and everything, just to cover all possibilities.

He didn’t suffer a scratch, but his room looked as though a bar-room brawl had been going on in it continually for fifty years.

Malley was working on an idea of his own, as was Darrig. The physicist interrupted himself long enough to remind Cercy of the Baldur myth. Baldur had been showered with every kind of weapon and remained unscathed, because everything on Earth had promised to love him. Everything, except the mistletoe. When a little twig of it was shot at him, he died.

Cercy turned away impatiently, but had an order of mistletoe sent up, just in case.

It was, at least, no less effective than the explosive shells or the bow and arrow. It did nothing except lend an oddly festive air to the battered room.

After a week of this, they moved the unprotesting Ambassador into a newer, bigger, stronger death cell. They were unable to venture into his old one because of the radioactivity and micro-organisms.

The Ambassador went back to work at his typewriter. All his previous attempts had been burned, torn or eaten away.

“Let’s go talk to him,” Darrig suggested, after another day had passed. Cercy agreed. For the moment, they were out of ideas.

“Come right in, gentlemen,” the Ambassador said, so cheerfully that Cercy felt sick. “I’m sorry I can’t offer you anything. Through an oversight, I haven’t been given any food or water for about ten days. Not that it matters, of course.”

“Glad to hear it,” Cercy said. The Ambassador hardly looked as if he had been facing all the violence Earth had to offer. On the contrary, Cercy and his men looked as though they had been under bombardment.

“You’ve got quite a defense there,” Malley said conversationally.

“Glad you like it.”

“Would you mind telling us how it works?” Darrig asked innocently.

“Don’t you know?”

“We think so. You become what is attacking you. Is that right?”

“Certainly,” the Ambassador said. “You see, I have no secrets from you.”

“Is there anything we can give you,” Cercy asked, “to get you to turn off that signal?”

“A bribe?”

“Sure,” Cercy said. “Anything you--?”

“Nothing,” the Ambassador replied.

“Look, be reasonable,” Harrison said. “You don’t want to cause a war, do you? Earth is united now. We’re arming--”

“With what?”

“Atom bombs,” Malley answered him. “Hydrogen bombs. We’re--”

“Drop one on me,” the Ambassador said. “It wouldn’t kill me. What makes you think it will have any effect on my people?”

The four men were silent. Somehow, they hadn’t thought of that.

“A people’s ability to make war,” the Ambassador stated, “is a measure of the status of their civilization. Stage one is the use of simple physical extensions. Stage two is control at the molecular level. You are on the threshold of stage three, although still far from mastery of atomic and subatomic forces.” He smiled ingratiatingly. “My people are reaching the limits of stage five.”

“What would that be?” Darrig asked.

“You’ll find out,” the Ambassador said. “But perhaps you’ve wondered if my powers are typical? I don’t mind telling you that they’re not. In order for me to do my job and nothing more, I have certain built-in restrictions, making me capable only of passive action.”

“Why?” Darrig asked.

“For obvious reasons. If I were to take positive action in a moment of anger, I might destroy your entire planet.”

“Do you expect us to believe that?” Cercy asked.

“Why not? Is it so hard to understand? Can’t you believe that there are forces you know nothing about? And there is another reason for my passiveness. Certainly by this time you’ve deduced it?”

“To break our spirit, I suppose,” Cercy said.

“Exactly. My telling you won’t make any difference, either. The pattern is always the same. An Ambassador lands and delivers his message to a high-spirited, wild young race like yours. There is frenzied resistance against him, spasmodic attempts to kill him. After all these fail, the people are usually quite crestfallen. When the colonization team arrives, their indoctrination goes along just that much faster.” He paused, then said, “Most planets are more interested in the philosophy I have to offer. I assure you, it will make the transition far easier.”

He held out a sheaf of typewritten pages. “Won’t you at least look through it?”

Darrig accepted the papers and put them in his pocket. “When I get time.”

“I suggest you give it a try,” the Ambassador said. “You must be near the crisis point now. Why not give it up?”

“Not yet,” Cercy replied tonelessly.

“Don’t forget to read the philosophy,” the Ambassador urged them.

The men hurried from the room.

“Now look,” Malley said, once they were back in the control room, “there are a few things we haven’t tried. How about utilizing psychology?”

“Anything you like,” Cercy agreed, “including black magic. What did you have in mind?”

“The way I see it,” Malley answered, “the Ambassador is geared to respond, instantaneously, to any threat. He must have an all-or-nothing defensive reflex. I suggest first that we try something that won’t trigger that reflex.”

“Like what?” Cercy asked.

“Hypnotism. Perhaps we can find out something.”

“Sure,” Cercy said. “Try it. Try anything.”

Cercy, Malley and Darrig gathered around the video screen as an infinitesimal amount of a light hypnotic gas was admitted into the Ambassador’s room. At the same time, a bolt of electricity lashed into the chair where the Ambassador was sitting.

“That was to distract him,” Malley explained. The Ambassador vanished before the electricity struck him, and then appeared again, curled up in his armchair.

“That’s enough,” Malley whispered, and shut the valve. They watched. After a while, the Ambassador put down his book and stared into the distance.

“How strange,” he said. “Alfern dead. Good friend ... just a freak accident. He ran into it, out there. Didn’t have a chance. But it doesn’t happen often.”

“He’s thinking out loud,” Malley whispered, although there was no possibility of the Ambassador’s hearing them. “Vocalizing his thoughts. His friend must have been on his mind for some time.”

“Of course,” the Ambassador went on, “Alfern had to die sometime. No immortality--yet. But that way--no defense. Out there in space they just pop up. Always there, underneath, just waiting for a chance to boil out.”