Before the car came to a stop Tiedus rummaged in a locker and stretched forth his hands as if carrying something delicate and fragile.

“It will be necessary for you to put this on,” he said:  “it will be unsafe otherwise.”

Blaine stared, mystified.  Was this Rulan kidding him?  “Put what on?” he asked.

“A thousand pardons.  I had forgotten that you do not know.  I hold in my hands a cloak, an invisible thing that will hide you from the guards and from the Zara’s crystal.  Another secret of my father’s.  Dantor developed it for him only recently.”

Blaine felt the texture of the stuff then; crumpled it in his fingers as its gossamer-like weight dropped in loose folds around his body.  But there was nothing there:  to the eyes.  It simply did not exist except to the touch, and he felt no different with it on than he had before.

“Where’s Tommy?” he asked suddenly, seeing that Dantus now sat alone at the controls.

Tiedus laughed.  “He has been covered in the same manner,” he said, “and is safely hidden from sight as are you.”

Incredulous, disbelieving, Blaine called out to his friend in a tremulous voice.  And Tom Farley’s awed response reassured him.

“Keep close to me,” Tiedus told him.  The car had stopped and he directed them into the basket of the lift.  The two Earth men collided violently and, clinging to each other in their ghastly invisibility, laughed crazily for a moment.  As far as any observers might know there were only the two Rulans in the basket.

Blaine fingered Pegrani’s ray pistol when the cable lowered them swiftly to the roof of a huge steel cylinder that rose, a solitary and unlovely structure, in the midst of the jungle a thousand miles from Ilen-dar.  The indicator informed him that seven energy charges still remained in the storage chamber of the little weapon.  Its possession brought him a measure of confidence.

Careful scrutiny of the roof had shown it to be deserted, so the basket was brought to rest in a deeply shadowed portion.  Immediately they stepped out, and it was sent swiftly aloft by remote control of a portable ether-wave that Dantor produced.

They encountered two of the green-bronze guards in one of the passages below and these challenged the Rulan lads with drawn pistols.  The alarm was out!  Fortunately Pegrani had not recognized Tiedus or all would have been lost.  But the Zara was watching every Rulan community and had instructed her guards to take the Earth men into custody at all costs.  Those remarkable cloaks were all that saved them.  They breathed easier when the guards passed on.

Now they were in a lift, dropping speedily into the depths of the Tritu Anu.  When the cage came to rest they were hustled into a maze of winding passageways that led ever downward.  A wall of damp stone finally blocked their progress, but at Dantus’ touch of a hidden spring a section of the solid rock swung aside to admit them to a concealed room where the lights were bright and where a delegation of Rulans awaited their coming.

With the cloaks of invisibility removed, they were welcomed by Dantor, a tall white-haired Rulan who was startlingly like his son.

They were a solemn lot, these Rulans of the older generation, but they gazed on the Earth men with sympathy and understanding.  An entirely different breed from the Llotta.

This room was a secret laboratory, fully equipped for chemical and physical research.  Dantor sat before a smaller replica of the Zara’s crystal ball as he addressed the visitors.

“No doubt you are puzzled,” he began, using the language of the Llotta with an accent that softened its harsh gutturals, “over the calamity that has befallen you.  And it is not to be wondered at.  But your own danger is as nothing compared with the danger that now threatens our whole solar system.  It is to explain that and to ask your cooperation in warding off the holocaust that I have sent for you.

“Since the destruction of the Tritu Nogaru we Rulans number less than one thousand, of whom three hundred are here.  The Tritu Anu is foremost of the royal laboratories of Llotta-nar and its work is carried out entirely by our people.  It is only on account of our superior accomplishments in science that the Llotta have allowed us to exist for so long a time, and, in this connection, I might say that the Zara has been taken severely to task for her wanton massacre of the Rulans of the Tritu Nogaru.  But that is neither here nor there; it is merely a sidelight I am giving you.

“The important thing is this k-metal of yours and its relation to the plans of the Llotta.  Antrid, as you know, is a dying world; coming rapidly to the end of its resources.  And, as our ancestors did before us, the Llotta have been casting their eyes about for a new home.  The inner planets beckoned, especially your Earth, but it was manifestly impossible to reach them as there is insufficient fuel in all Antrid to provide for the voyage of even one space ship.  Then, with the long range searching rays of the crystal ball television and sound reproducers, they discovered the use of this k-metal.  The sending of Antazzo to your Earth followed.

“The rest you know insofar as his activities are concerned, but what you do not know is this:  The Llotta have constructed a huge steel tube that is set deep into the crust of Antrid; an enormous rocket-tube if you please, like one of those on your space ship.  They plan to use the energy of this supply of k-metal in setting up tremendous streams of electronic discharges from the great tube and thus to swing the satellite from its natural orbit.  They would send this entire world hurtling through space toward the inner planets, and, by proper control of the rocket discharges, bring it close to your Earth where it would become a secondary satellite at close range.  Then they could war on you at their leisure and finally take Earth as their new home.  Thus have the Llotta planned.”

“What!” Blaine exclaimed.  “Why, we’d blast them from the skies before they were started.  They haven’t a chance.”

Dantor nodded gravely.  “I am sure of it,” he agreed:  “I have seen your great guns in the crystal.  But they are blind to that possibility.  And there are other serious flaws in the plan.  The incentive, of course, lies in the certain knowledge that we are using up the internal heat of Antrid so rapidly that less than a century of life now remains to its peoples.  Our power is produced by admitting water to the interior through myriads of tubes that serve the double purpose of introducing the water and conveying the generated steam back to the surface, where it produces electricity by driving great turbine generators.  This electricity is distributed by charging the copper shell and the ground beneath at high frequency; it is collected from the air between by the heaters and various machines that use it.  But the shortage is ever more serious and Antrid is cooling off.  Thus the need for the k-metal and thus the sending of Antazzo.  And now for the flaws: 

“The Zara, in killing Antazzo, frustrated her own plans, as he alone, of all her people, knew how to use this marvelous energy producer.  Realizing this, she set about to make friends with you two in the hope that the information might be obtained from you.  That was a great mistake and raised an unexpected obstacle.”

“Well, I’ll be damned!” Blaine exploded.  “No wonder she tried her wiles on me.  Tried to make a sucker out of me, didn’t she?”

Dantor smiled knowingly.  “More about Clyone later,” he said.  “Actually she is enamoured of you, Carson, and besides she is not really responsible for the mad plan herself.  But that tale can wait.

“The basic and most serious flaw in the plan is this:  It can not possibly succeed, no matter how successful their attempts.  What they do not understand and will not believe when I tell them is that the only result of the mad experiment will be the complete destruction of the solar system, Antrid and themselves included.  Complete and horrible annihilation, I say!” Dantor paused and eyed his visitors solemnly.

In his mind’s eye, Blaine could not visualize such a thing nor picture the possible explanation.  But he saw that Tommy had paled and was clenching his fists.  Tommy was more of a scientist; it must be he realized what this enterprise involved.

Dantor was speaking again, in low, intense tones:  “What they are refusing to see is that the delicate balance of the solar system will be disturbed if a body as large as Antrid is moved a half billion miles sunward.  All bodies are kept in their orbits by a nice balance of mass attraction and centrifugal force; if a single one is altered all others are affected.  What would happen is easy to calculate.  First off, when Antrid approached the inner planets all bodies in the system would change their paths and the altered forces would cause severe earthquakes, tidal waves and other natural disturbances of disastrous extent.

“These would increase in violence as Antrid drew nearer to the sun, and, if she finally took up her position as a new satellite of the Earth, the entire solar system would be in chaos.  By this time, even if life still remained on Earth, it would quickly become extinct, for the vastly increased tidal forces on that body would flood the land to the peaks of the highest mountains.  Earth would draw in closer to the sun due to loss of velocity and increased mass of the Earth-moon system.  Tremendous new forces would rend asunder the Earth, its moon, and Antrid.  Venus and Mars, following suit as the forces equalized, we would have a dead universe.”

Tommy believed him.  That was apparent from his furrowed brow and grim set jaw.  “I’ll never give ’em the secret of the k-metal,” he grated.  “Nor will Carson; I’ll gamble on that.  We’ll die here before they’ll get it out of us.”

Blaine seconded his remarks fervently.  Then, turning to the Rulan scientist, “Perhaps,” he suggested, “we might remain in hiding here for an indefinite period.  Perhaps even we might contrive a way of getting to the store of k-metal and regaining possession of it.  They’d be licked for sure then.”

Dantor beamed.  “That is exactly why I sent for you,” he said.  Then sobering anew, he added, “But I fear that would not be the end.  They will not give up.  Another emissary would be transmitted to duplicate Antazzo’s exploit on Earth and in five of your years the danger would again be faced.  They would take infinite precaution to prevent a second failure.  We must make it forever impossible-now.”

“How can we?  My God, it’s hopeless!” Blaine groaned.

“Nothing is hopeless, my boy.  Consider the plight of the Rulans.  No, there is still hope and we will leave you to think it over-if you are willing.  It is necessary that we Rulans show our faces above before we arouse the suspicions of the guards.”

“Of course we’re willing.  We’ll stay as long as you say-and help.”  Blaine was intensely earnest and Tommy chimed in with his old time fervor and enthusiasm.  But hope of success seemed remote.

A murmur of approval came from the assembled Rulans, and Dantor wiped a trace of moisture from his tired old eyes.  “Thank you,” he said simply.  “This chamber is insulated from the searching rays of the crystal spheres.  You are safe for the present and will be supplied with everything you need.  And I shall return shortly to discuss the matter in further detail.”

The two Earth men were alone then, in the uncanny silence of the underground retreat, regarding each other with awed comprehension.  What patient, hopeless creatures these Rulans were!  Knowing they were doomed, and without thought of their own safety, they were bending their every effort to the impossible task of saving the universe from the madness of the Llotta.

“What do you know about that?” Tommy said, after a while.

“It’s true, what he said?” Blaine asked.  “What would happen to our world, I mean-and to the rest?”

“Not a question of doubt.  He’s doped it out to a T. Smart guy, this Dantor.”

“What do you think?  Is there a chance?  Think-

“Hush!” Tommy interrupted him.  “Didn’t you hear something?”

The silence was ghastly; depressing.  Blaine heard distinctly the beating of his own heart.

Then it was there again, that sound-a muffled scream from the other side of the stone door.  A woman’s scream of desperate entreaty.  A shuddering, long-drawn moan, trailing off into deathly silence.