Jhal Arn looked through the open door with Gordon from the threshold.

“There it is, the same as ever,” he said with a strong tinge of awe in his voice.

The room was a small, round one hollowed also from solid rock and also lighted by throbbing white radiance from wall plates.

Gordon perceived at the center of the room the group of objects at which Jhal Arn was gazing with such awe.

The Disruptor! The weapon so terrible that its power had only once been unloosed in two thousand years.

“But what is it?” Gordon wondered dazedly, as, he stared.

There were twelve big conical objects of dull gray metal, each a dozen feet long. The apex of each cone was a cluster of tiny crystal spheres. Heavy, varicolored cables led from the bases of the cones.

What complexities of unimaginable science lay inside the cones, he could not even guess. Beside heavy brackets for mounting them, the only other object here was a bulky cubical cabinet on whose face were mounted a bank of luminous gauges and six rheostat switches.

“It draws such tremendous power that it will have to be mounted on a battleship, of course,” Jhal Arn was saying thoughtfully. “What about the Ethne you came in? Wouldn't its turbines provide enough power?

Gordon floundered. “I suppose so. I'm afraid I'll have to leave all that to you.”

Jhal Arn looked astounded. “But Zarth, you're the scientist of the family. You know more about the Disruptor than I do.”

Gordon hastily denied that. “I'm afraid I don't now. You see, it's been so long that I've forgotten a lot about it.”

Jhal Arn looked incredulous. “Forgotten about the Disruptor? You must be joking. That's one thing we don't forget. Why, it's drilled into our minds beyond forgetfulness on the day when we're first brought down here to have the Wave tuned to our bodies!”

The Wave? What was that? Gordon felt completely at sea in his ignorance.

He advanced a hasty explanation. “Jhal, I told you that Shorr Kan used a brain scanning device to try to learn the Disruptor secret from me. He couldn't-but in my deliberate effort to forget it so he couldn't, I seem really to have lost a lot of the details.”

Jhal Arn seemed satisfied by the explanation. “So that's it. Mental shock, of course. But of course you still remember the main nature of the secret. Nobody could forget that.”

“Of course, I haven't forgotten that,” Gordon was forced to prevaricate hastily.

Jhal drew him forward. “Here, it will all come back to you. These brackets are for mounting the force-cones on a ship's prow. The colored cables hook to the similarly colored binding-posts on the control panel, and the transformer leads go right back to drive-generators.” He pointed at the gauges. “They give the exact coordinates in space of the area to be affected. The output of the cones has to balance exactly, of course. The rheostats do that-”

As he went on, John Gordon began dimly to perceive that the cones were designed to project force into a selected area of space.

But what kind of force? What did they do to the area or object on which they acted, that was so awful? He dared not ask that.

Jhal Arn was concluding his explanation. “-so the target area must be at least ten parsecs from the ship you work from, or you'll get the backlash. Don't you remember it all now, Zarth?”

Gordon nodded hurriedly. “Of course. But I'm glad just the same that it will be your job to use it.”

Jhal looked more haggard. “God knows I don't want to. It has rested here all these centuries without being used. And the Warning of Brenn Bir still is true.”

He pointed up, as he spoke, to an inscription on the opposite wall. Gordon read it now for the first time.

“To my descendants who will hold the secret of the Disruptor that I, Brenn Bir, discovered: Heed my warning. Never use the Disruptor for petty personal power. Use it only if the freedom of the galaxy is menaced.

“This power you hold could destroy the galaxy. It is a demon so titanic that once unchained, it might not be chained again. Take not that awful risk unless the life and liberty of all men are at stake!”

Jhal Arn's voice was solemn. “Zarth, when you and I were boys and were first brought down here by our father to have the Wave tuned to us, we little dreamed that a time might come when we would think of using that which has lain here for so long.”

His voice rang deeper. “But the life and liberty of all men are at stake, if Shorr Kan seeks to conquer the galaxy. If all else fails, we must take the risk!”

Gordon felt shaken by the implications of that warning. It was like a voice of the dead', speaking heavily in this silent room. Jhal turned and led the way out of the room. He closed the door and again Gordon wondered. No lock, no bolts, no guard.

They went down the long radiant corridor and emerged from it into the softer yellow light of the well of the spiral stair.

“We'll mount the equipment on the Ethne tomorrow morning,” Jhal Arn was saying. “When we show the star-kingdom envoys-”

“You will never show them anything, Jhal Arn.”

Out from beneath the spiral stair had sprung a disheveled man who held an atom-pistol leveled on Gordon and Jhal Arn.

“Orth Bodmer!” said Gordon. “You were hiding in the palace all the time.”

Orth Bodmer's thin face was colorless, deadly, twitching in a pallid smile.

“Yes, Zarth,” he grated. “I knew the game was up when I saw Thern Eldred brought in. I couldn't get out of the palace without being swiftly traced and apprehended, so I hid in the deeper corridors.”

His smile was ghastly now. “I hid, until as I had hoped you came down here to the Chamber of the Disruptor, Jhal Arn. I've been waiting for you.”

Jhal's eyes flashed. “Just what do you expect to gain by this?”

“It is simple,” rasped Bodmer. “I know my life is forfeit. Well, so is your life unless you spare mine.”

He stepped closer, and Gordon read the madness of fear in his burning eyes.

“You do not break your word when it is given, high ness. Promise me that I shall be pardoned, and I will not kill you now.” Gordon saw that panic had driven this rabbity, nervous traitor to insane resolve.

“Jhal, do it!” he said. “He's not worth risking your life for.”

Jhal Arn's face was dull red with fury. “I have let one traitor go free, but no more.”

Instantly, before Gordon could voice the cry of appeal on his lips, Orth Bodmer's atom-pistol crashed.

The pellet tore into Jhal Arn's shoulder and exploded there as Gordon plunged forward at the maddened traitor.

“You murdering lunatic,” cried Gordon fiercely, seizing the other's gun-wrist and grappling with him.

For a moment, the thin Councilor seemed to have superhuman strength. They swayed, stumbled, and then reeled together from the hall into the brilliant white radiance of the long corridor.

Then Orth Bodmer screamed. He screamed like a soul in torment, and Gordon felt the man's body relax horribly in his grasp.

“The Wave!” screeched Bodmer, staggering in the throbbing radiance.

Even as the man screamed, Gordon saw his whole body and face horribly blacken and wither. It was a shriveled, lifeless body that sank to the floor.

So ghastly and mysterious was that sudden death, that for a moment Gordon was dazed. Then he suddenly understood.

The throbbing radiance in the corridor and in the Chamber of the Disruptor was the Wave that Jhal Arn had spoken of. It was not light but a terrible, destroying force-a force so tuned to individual human bodily vibrations that it blasted every human being except the chosen holders of the Disruptor secret.

No wonder that no locks or bolts or guards were needed to protect the Disruptor! No man could approach it without being destroyed, except Jhal Arn and Gordon himself. No, not John Gordon but Zarth Arn-it was Zarth Arn's physical body that the Wave was tuned to spare.