"I am Greca"--it was very hard to grasp names or abstract terms--"of the fourth satellite."

"Then you are not of these monsters of Jupiter?"

"Oh, no! I am their captive, as are all my people. We are but slaves of the tall ones."

Brand glanced at Dex. "Here's a chance to get some information, perhaps," he murmured.

Dex nodded; but meanwhile the girl had caught his thought. She smiled--a tragic, wistful smile.

"I shall be happy to tell you anything in my power to tell," she informed him. "But you must be quick. I can only remain with you a little while."

She sat down on the floor with them--the few bench-like things obviously used by the tall creatures as chairs were too high for them--and with the informality of adversity the three captives began to talk. Swiftly Brand got a little knowledge of Greca's position on Jupiter, and of the racial history that led up to it.

Four of the nine satellites of Jupiter were now the home of living beings. But two only, at the dawn of history as Greca knew it, had been originally inhabited. These were the fourth and the second.

On the fourth there dwelt a race, "like me," as Greca put it--a kindly, gentle people content to live and let live.

On the second had been a race of immensely tall, but attenuated and physically feeble things with great heads and huge dull eyes and characters distinguished mainly for cold-blooded savagery.

The inhabitants of the fourth satellite had remained in ignorance of the monsters on the second till one day "many, many ages ago," a fleet of clumsy ships appeared on the fourth satellite. From the ships had poured thousands of pipe-like creatures, armed with horrible rods of metal that killed instantly and without a sound. The things, it seemed, had crowded over the limits of their own globe, and had been forced to find more territory.

They had made captive the entire population of the satellite.

Then--for like all dangerous vermin they multiplied rapidly--they had overflowed to the first and fifth satellites--the others were uninhabitable--and finally to the dangerous surface of Jupiter itself.

Everywhere they had gone, they had taken droves of Greca's people to be their slaves, "and the source of their food," added Greca, with a shudder; a statement that was at the moment unintelligible to the two men.

Brand stared sympathetically at her. "They treat them very badly?" he asked gently.

"Terribly! Terribly!" said Greca, shuddering again.

"But you seem quite privileged," he could not help saying.

She shook her dainty head pathetically. "I am of high rank among my people. I am a priestess of our religion, which is the religion of The Great White One who rules all the sky everywhere. The Rogans" (it was the best translation Brand could make of her mental term for the slimy tall things that held them captive) "--the Rogans hold my fate over the heads of my race. Should they rebel, I would be thrown to the monster in the pen. Of course the Rogans could crush any revolt with their terrible tubes, but they do not want to kill their slaves if they can help it. They find it more effective to hold their priestesses in hostage."

Brand turned from personal history to more vital subjects.

"Why," he asked Greca, "are the shining red squares of metal laid everywhere over this empire of the Rogans?"

"To make things light," was the reply. "When the Rogans first came to this mighty sphere, they could hardly move. Things are so heavy here, somehow. So their first thought was to drive my enslaved people to the casting and laying of the metal squares and the metal beams that connect them, in order to make things weigh less."

"But how do the plates function?"

Greca did not know this, save vaguely. She tried to express her little knowledge of the scientific achievements of the savage Rogans. After some moments Brand turned to Dex and said:

"As near as I can get it, the Rogans, by this peculiar red metal alloy, manage to trap and divert the permanent lines of force, the magnetic field, of Jupiter itself. So the whole red spot is highly magnetized, which somehow upsets natural gravitational attraction. I suppose it is responsible for the discoloration of the ground, too."

He turned to question the girl further about this, but she had got nervously to her feet already.

"I'll be taken away soon," she said. "I was brought in here only to urge you to eat the food. I must be interpreter, since the Rogans speak not with the mind, and I know their hateful tongue."

"Why are they so anxious for us to eat?" demanded Dex with an uneasy frown.

"So you will be strong, and endure for a long time the--the ordeal they have in store for you," faltered the girl at last. "They intend to force from you the secret of the power that drove your ship here, so they too may have command of s.p.a.ce."

"But I don't understand," frowned Brand. "They must already have a means of s.p.a.ce navigation. They came here to Jupiter from the satellites."

"Their vessels are crude, clumsy things. The journey from the nearest satellite is the limit of their flying range. They have nothing like your wonderful little ships, and they want to know how to build and power them."

She gazed sorrowfully at them and went on: "You see, yours is the fourth s.p.a.ce ship to visit their kingdom; and that makes them fearful because it shows they are vulnerable to invasion. They want to stop that by invading your planet first. Besides their fear, there is their greed. Their looking-tubes reveal that yours is a fruitful and lovely sphere, and they are insatiable in their l.u.s.t for new territories.

Thus they plan to go to your planet as soon as they are able, and kill or enslave all the people there as they have killed and enslaved my race."

"They'll have a job on their hands trying to do that!" declared Dex stoutly.

But Brand paled. "They can do it!" he snapped. "Look at those death-tubes of theirs. We have no arms to compete with that." He turned to Greca. "So the Rogans plan to force the secret of our motors from us by torture?"

She nodded, and caught his hand in hers.

"Yes. They will do with you as they did with the six who came before you--and who died before surrendering the secret."

"So! We know now what happened to Journeyman and the others!" burst out Dex. "I'll see 'em in h.e.l.l before I'll talk!"

"And me," nodded Brand. "But that doesn't cure the situation. As long as ships disappear in this red inferno, so long will the Old Man keep sending others to find out what's wrong. The Rogans will capture them as easily as they captured us. And eventually someone will happen along who'll weaken under torture. Then--"

He stopped. A dread vision filled his mind of Earth depopulated by the feebly ferocious Rogans, of rank on rank of Earth's vast armies falling in stricken rows at the shock of the Rogans' tubes.

Greca caught the vision. She nodded. "Yes, that is what would happen if they found ways of reaching your globe."

"But, G.o.d, Brand, we can't allow that!" cried Dex. "We've got to find a way to spike the guns of these walking gas-pipes, somehow!"

Brand sighed heavily. "We are two against hundreds of thousands. We are bare-handed, and the Rogans have those d.a.m.ned tubes. Anyway, we are on the verge of death at this very moment. What under heaven can we do to spike their guns?"

He was silent a moment: and in the silence the steady hum from the domed building outside came to his ears.

"What's in that big, round topped building, Greca?" he asked quietly.

"I do not know, exactly," replied the girl. "There is some sort of machinery in it, and to it go connecting beams from all the square metal plates everywhere. That is all I know."

Brand started to question her further, but her time was up. The two guards poked their loathsome pumpkin heads in the doorway and contemptuously beckoned her out. She answered resignedly, in the piping Rogan tongue, and went with them. But she turned to wave shyly, commiseratingly at the two men; and the expression in her clear blue eyes as they rested on Brand made his heart contract and then leap on with a mighty bound.