For it was a gigantic dome of black metal rising sheer from the lonely sea, ten miles if anything in diameter, a third that in greatest height. There was no gate or window or opening of any kind in it. Just the colossal, smooth black dome rearing from the watery plain. Yet the two boats were flashing lower toward it.
"They can't be going inside!" Hackett conjectured. "There's no way in and what could be in there? The whole thing's mad--"
"There's some way," Norman said. "They're slowing--"
The flying-boats were indeed slowing as they dipped lower. They were very near the dome now, its curving wall a looming, sky-high barrier before them. Suddenly the boats dipped sharply downward toward the green sea. Before the two fliers could comprehend their purpose, could do aught more than draw instinctive great breaths in preparation, the two craft had shot down into the waters and were arrowing down through the green depths.
Blinded, flung against his metal strap by the resistance of the waters they ripped through, Norman yet retained enough of consciousness to glimpse beams of light that stabbed ahead from the prows of their rushing boats, to see vaguely strange creatures of the deep blundering in and out of those beams as the boats hurtled forward. The water that forced its way between his lips was fresh, he was vaguely aware, and even as he fought to hold his breath was aware too that the frog-men seemed in no way incommoded by the sudden transition into the water, their amphibian nature allowing them to stay under it far longer than any human could do.
The boats ripped through the waters at terrific speed and in a few seconds there loomed before them the giant metal wall of the great dome, going down into the depths here. Norman glimpsed vaguely that the whole colossal dome rested on a vast pedestal-like mountain of rock that rose from the sea's floor almost to the surface. Then a great round opening in the wall; the boats flashed into it and were hurtling along a water-filled tunnel. Norman felt his lungs near bursting--when the tunnel turned sharply upward and the boats whizzed up and abruptly out of the water-tunnel into air!
But it was not the open air again. They were beneath the gigantic dome! For as Norman and Hackett breathed deep, awe fell on their faces as they took in the scene. Far overhead stretched the dome's colossally curving roof, and far out on all sides. It was lit beneath that roof by a clear light that the two would have sworn was sunlight. The dome was in effect the roof of a gigantic, illuminated building, and upon its floor there stretched a mighty city.
The city of the frog-men! Their boats were rising up over it and Norman and Hackett saw it clear. Square mile upon square mile of structures stretched beneath the dome, black buildings often of immense size, varying in shape, but all of square, rectangular proportions. Between them moved countless frog-hordes, swirling throngs in streets and squares, and over the roofs darted thick swarms of flying-boats. And at the city's center, in a great, circular, clear space, lay a wide, round, green pool--the opening of the water-tunnel up through which they had come.
Norman pointed down toward it. "That's your answer!" he cried. "The only entrance to this frog-city is from the sea, up through that water-tunnel!"
"Good God, an amphibian city!" Hackett was shaken, white-faced.
The two boats were driving quickly over the city, through the swarming craft. Norman glimpsed towering buildings that might have been palaces, temples, laboratories. They slowed and dipped toward one block-like building not far from the water-tunnel's opening. Armed frog-guards were on its roof, and other boats rested there. The two came to rest and the two captives were jerked out, the guards seizing them.
Half-dragged and half-floating they were led toward an opening in the roof from which a stair led downward. They passed down thus into the building's interior, lit by many windows. Norman glimpsed long halls ending in barred doors, guards here and there. Tube-lines ran along the walls and somewhere machines were throbbing dully. They came at last to a barred door whose guard opened it at the croaking order of the frog-men who held the two, and they were thrust inside, as the door clanged. They turned, and exclaimed in amazement. The room held fully a half-hundred men!
They were men such as the two fliers had never seen before, like humans except that their skins were a light green instead of the normal white and pink. They were dressed in dark short tunics, and kept talking to each other in a tongue quite unintelligible to Norman and Hackett. They came closer, flocking curiously around the two men, with a babel of voices quite meaningless to the two. Then one of the men uttered an exclamation, and all turned.
The barred door had swung open and a half-dozen frog-guards entered, followed by two frog-men carrying a square little mechanism from which tubing led back out through the door.
"Norman--these men--" Hackett was whispering rapidly. "If there are men in this world too, it may be that--"
"Quiet, Hackett--look at what they're doing."
The two frog-men had set their mechanism in place and then croaked out a brief word or order. Slowly, reluctantly, one of the green men moved toward them. Quickly they removed a metal disk fastened to his arm, exposing a small orifice like an unhealed wound. Onto this they fastened a suckerlike object from which a transparent tube led back through the mechanism. The machine hummed and at once a red stream pulsed through the tube and back through the mechanism. The man to whom it was attached was growing rapidly pale!
Norman, sick with horror, clutched his companion. "Hackett--these frog-men are sucking his blood from him!"
"Good God! And look--they're doing it with another!"
"All of these men--kept prisoners to furnish them with blood. It must be the damned creatures' food! And we here with the others--"
A common horror shook the two. It did not seem to affect the green men in the room, though, who advanced to the mechanism one by one with a reluctant air as of cows unwilling to be milked. Each was attached to the mechanism by the sucking disk on his arm, and out of each the blood poured through the tube. The metal disk was replaced on his arm then and he went back to the others. Norman saw that the frog-men took only from each an amount of blood that they could lose and yet live, since, though each came back pale and weak from the mechanism, they were able to walk.
"It must be their food--human blood!" Norman repeated. "They may have thousands on thousands of humans penned up like this, like so many herds of cows, and perhaps they live entirely on the life-blood they milk from them. Human cows--God!"
"Norman--look--they're calling to us!"
The two stiffened. All the others in the room had taken their turn at the blood-sucking mechanism and now the frog-men croaked their order to the two fliers. They had forgotten their own predicament in the horror of the scene, but now it became real to them. They backed against the room's wall, quivering, dangerous.
The frog-guards came forward to drag them to the machine. A webbed paw was outstretched but Hackett with a wild blow drove the frog-man back and downward. The frog-guards leaped, and Norman and Hackett struck them back with all the greater strength the lesser gravitation gave them. The room was in an uproar, the green men shouting hoarsely and seeming on the point of rushing to their aid.
But the menacing force-pistols of the other frog-guards held back the shouting men and in moments the two fliers were overpowered by sheer weight of frog-bodies. Norman felt himself dragged to the machine.
Pain needled his upper arm as an incision was made. He felt the sucking-disk attached; then the machine hummed, and a sickening nausea swept him as the blood drained from his body. Held tightly by the guards he went dizzy, weak, but at last felt the sucker removed and a metal disk fastened over the incision. He was jerked aside and Hackett, his face deathly white, was dragged into his place. In a moment some of the latter's blood had been pumped from him also.
The machine was withdrawn, Norman and Hackett were released, and the frog-men, with their black force-pistols watchfully raised, withdrew, the door clanging. The room settled back to quietness, the green men stretching in lassitude on the metal bunks around it. The two fliers crouched down near the door, shuddering nausea and weakness still holding them.
Norman found that Hackett was laughing weakly. "To think that twenty-four hours ago I was in New York," he half-laughed, half-sobbed. "On Earth--Earth--"
The other gripped his arm. "It's horrible, Hackett, I know. But it isn't instant death, and we've still a chance to escape. Hell, can damn frog-men keep us here? Where's your nerve, man?"
A voice beside them made them turn in amazement. "You are men from Earth?" it asked, in queerly accented English. "From Earth?"
Astonishment held them as they saw who spoke. It was one of the green men in the room, who had settled down by their side. A tall figure with superb muscles and frank, clean countenance, his dark eyes afire with eagerness.
"English?" Norman exclaimed. "You know English--you understand me?"
The other showed his teeth in a smile. "I know, yes. I'm Sarja, and I learned to speak it from Fallas, in my city, before the Ralas caught me."
"Fallas--" Norman repeated, puzzled; then suddenly he flamed. "By God, he means Fellows!"
"Fallas, yes," said the other. "From the sky he fell into our city in a strange flying-boat that was smashed. He was hurt but we cared for him, and he taught me his speech, which I heard you talking now."
"Then Fellows is in your city now?" asked Hackett eagerly. "Where is that?"
"Across this sea--back in the hills," the other waved. "It is far from the sea but I was rash one day and came too near the water in my flying-boat. The Ralas were out raiding and they saw me, caught me, and brought me here. No escape now, until I die."
"The Ralas--you mean these frog-men?" Norman asked.
Sarja nodded. "Of course. They are the tyrants and oppressors of this world. Our little world is but a tenth or less the size of your great Earth which it circles, but it has its lands and rivers, and this one great fresh-water sea into which the latter empty. In this sea long ago developed the Ralas, the great frog-men who acquired such intelligence and arts that they became lords of this world.
"Through the centuries, while on the land our races of green men have been struggling upward, the Ralas have oppressed them. Long ago the Ralas left all their other cities to build this one great amphibian city at the sea's center. Entrance to it is only by the water-tunnel from without, and being frog-people entrance thus is easy for them since they can move for many minutes under water, though they drown like any other breathing animal if kept under too long. Humans dare not try to enter it thus by the water-tunnel, since, before they could find it and make their way up through it, they would have drowned.
"So the Ralas have ruled from this impregnable amphibian city. Its colossal metal dome is invulnerable to ordinary attack, and though solid and without openings it is always as light beneath the dome here as outside, since the Ralas' scientists contrived light-condensers and conductors that catch light outside and bring it in to release inside. So when it is day outside the sunlight is as bright here, and when night comes the Earth-light shines here the same as without.
"From this city their raiding parties have gone out endlessly to swoop down on the cities of us green men. Since we learned to make flying-boats like theirs, with molecular-motors, and to make the guns like theirs that fire shells filled with annihilating force, we have resisted them stoutly but their raids have not ceased. And always they have brought their prisoners back in to this, their city.
"Tens of thousands of green men they have prisoned here like us, for the sole purpose of supplying them with blood. For the Ralas live on this blood alone, changing it chemically to fit their own bodies and then taking it into their bodies. It eliminates all necessity for food here for them. Every few days they drain blood from us, and since we are well fed and cared for to keep us good blood-producers, we will be here for a long time before we die."
"But haven't you made any attempt to get out of here--to escape?" Norman asked.
Sarja smiled. "Who could escape the city of the Ralas? In all recorded history it has never been done, for even if by some miracle you got a flying-boat, the opening of the water-tunnel that leads outward is guarded always."
"Guards or no guards, we're going to try it and not sit here to furnish blood for the Ralas," Norman declared. "Are you willing to help, to try to get to Fellows and your city?"
The green man considered. "It is hopeless," he said, "but as well to die beneath the force-shells of the Ralas as live out a lifetime here. Yes, I will help, though I cannot see how you expect to escape even from this room."
"I think we can manage that," Norman told him. "But first--not a word to these others. We can't hope to escape with them all, and there is no knowing what one might not betray us to the frog-men."
He went on then to outline to the other two the idea that had come to him. Both exclaimed at the simpleness of the idea, though Sarja remained somewhat doubtful. While Hackett slept, weak still from his loss of blood, Norman had the green man scratch on the metal floor as well as possible a crude map of the satellite's surface, and found that the city, where Fellows was, seemed some hundreds of miles back from the sea.
While they talked, the sunlight, apparently sourceless, that came through the heavily barred windows of the room faded rapidly, and dusk settled over the great amphibian city beneath the giant dome, kept from total darkness by a silvery pervading light that Norman reflected must be the light from Earth's great sphere. With the dusk's coming the activities in the frog-city lessened greatly.
With dusk, too, frog-guards entered the room bearing long metal troughs filled with a red jellylike substance, that they placed on racks along the wall. As the guards withdrew the men in the room rushed toward the troughs, elbowing each other aside and striking each other to scoop up and eat as much of the red jelly as possible. It was for all the world like the feeding of farm-animals, and Hackett and Norman so sickened at the sight that they had no heart to try the food. Sarja, though, had no such scruples and seemed to make a hearty meal at one of the troughs.
After the meal the green men sought the bunks and soon were stretched in sonorous slumber. It was, Norman reflected, exactly the existence of domesticated animals--to eat and sleep and give food to their masters. A deeper horror of the frog-men shook him, and a deeper determination to escape them. He waited until all in the room were sleeping before beckoning to Sarja and Hackett.
"Quiet now," he whispered to them. "If these others wake they'll make such a clamor we won't have a chance in the world. Ready, Sarja?"
The green man nodded. "Yes, though I still think such a thing's impossible."
"Probably is," Norman admitted. "But it's the one chance we've got, the immensely greater strength of our Earth-muscle that the frog-men must have forgotten when they put us in here."
They moved silently to the room's great barred door, outside which a frog-guard paced. They waited until he had passed the door and on down the hall, then Norman and Hackett and Sarja grasped together one of the door's vertical bars. It was an inch and a half in thickness, of solid metal, and it seemed ridiculous that any men could bend it by the sheer strength of their muscles.
Norman, though, was relying on the fact that on the second satellite, with its far lesser gravitational influence, their Earth-muscles gave them enormous strength. He grasped the bar, Hackett and Sarja gripping it below him, and then at a whispered word they pulled with all their force. The bar resisted and again, with sweat starting on their foreheads, they pulled. It gave a little.
They shrank back from it as the guard returned, moving past. Then grasping the bar again they bent all their force once more upon it. Each effort saw it bending more, the opening in the door's bars widening. They gave a final great wrench and the bent bar squealed a little. They shrank back, appalled, but the guard had not heard or noticed. He moved past it on his return along the hall, and no sooner was past it than Norman squeezed through the opening and leaped silently for the great frog-man's back.
It went down with a wild flurry of waving webbed paws and croaking cries, stilled almost instantly by Norman's terrific blows. There was silence then as Hackett and Sarja squeezed out after him, the momentary clamor of the battle having aroused no one.
The three leaped together toward the stairs. In two great floating leaps they were on the floor above, Hackett and Norman dragging Sarja between them. They were not seen, were sailing in giant steps up another stair, hopes rising high. The last stair--the roof-opening above; and then from beneath a great croaking cry swelled instantly into chorus of a alarmed shouts.
"They've found the door--the guard!" panted Hackett.
They were bursting out onto the roof. Frog-guards were on it who came in a hopping rush toward them, force-pistols raised. But a giant leap took Hackett among them, to amaze them for a moment with great flailing blows. Sarja had leaped for the nearest flying-boat resting on the roof, and was calling in a frantic voice to Norman and Hackett. Norman was turning toward Hackett, the center of a wild combat, but the latter emerged from it for a brief second to motion him frantically back.
"No use, Norman--get away--get away!" he cried hoarsely, frenziedly.
"Hackett--for God's sake--!" Norman half-leaped to the other, but an arm caught him, pulled him desperately onto the boat's surface. It was Sarja, the long craft flying over the roof beneath his control.
"They come!" he panted. "Too late now--" Frog-men were pouring up onto the roof from below. Sarja sent the craft rocketing upward, as Hackett gestured them away for a last frantic time before going down beneath the frog-men's onslaught.
The roof and the combat on it dropped back and beneath them like a stone as their craft ripped across the silvery dusk over the mighty frog-city. They were shooting toward the city's center, toward the green pool that was the entrance to the water-tunnel, while behind and beneath an increasing clamor of alarm spread swiftly. Norman raged futilely.
"Hackett--Hackett! We can't leave him--"
"Too late!" Sarja cried. "We cannot help him but only be captured again. We escape now and come back--come back--"
The truth of it pierced Norman's brain even in the wild moment. Hackett had fought and held back the frog-guards only that they might escape. He shouted suddenly.
"Sarja--the water-tunnel!" A half-dozen boats with frog-guards on them were rising round it in answer to the alarm!
"The force-gun!" cried the green man. "Beside you--!"
Norman whirled, glimpsed the long tube on its swivel beside him, trained it on the boats rising ahead as they rocketed nearer. He fumbled frantically at a catch at the gun's rear, then felt a stream of shells flicking out of it. Two of the boats ahead vanished as the shells released their annihilating force, another sagged and fell. From the remaining three invisible force-shells flicked around them, but in an instant Sarja had whirled the boat through them and down into the water-tunnel!
Norman clung desperately to his seat as the boat flashed down through the waters, and then, as Sarja sent it flying out through the great tunnel's waters, glimpsed, close behind, the beams of the three Rala boats as they pursued them through the tunnel, overtaking them. Could the force-shells be fired under water? Norman did not know, but desperately he swung the force-gun back as they rushed through the waters, and pressed the catch. An instant later beams and boats behind them in the tunnel vanished.
His lungs were afire; it seemed that he must open them to the strangling water. The boat was ripping the waters at such tremendous speed that he felt himself being torn from his hold on it. Pain seemed poured like molten metal through his chest--he could hold out no longer; and then the boat stabbed up from the waters into clear air!
Norman panted, sobbed. Behind them rose the colossal metal dome of the frog-city, gleaming dully in the silvery light that flooded the far-stretching seas. That light poured down from a stupendous silver crescent in the night skies. Norman saw dully the dark outlines on it before he remembered. Earth! He laughed a little hysterically. Sarja was driving the flying-boat out over the sea and away from the frog-city at enormous speed. At last he glanced back. Far behind them lay the great dome and up around it gleaming lights were pouring, lights of pursuing Rala boats.
"We escape," Sarja cried, "the city of the Ralas, from which none ever before escaped!"
Remembrance smote Norman. "Hackett! Held off those frog-men so we could get away--we'll come back for him, by God!"
"We come back!" said Sarja. "We come back with all the green men of this world to the Ralas' city, yes! I know what Fallas has planned."
"Can you find your way to him--to your city?" Norman asked.
Sarja nodded, looking upward. "Before the next sun has come and gone we can reach it."
The boat flew onward, and the great dome and the searching lights around it dropped beneath the horizon. Norman felt the warm wind drying his drenched garments as they rushed onward. Crouched on the boat he gazed up toward the silver crescent of Earth sinking toward the horizon ahead. That meant, he told himself, that the satellite turned slowly on its axis as it whirled around Earth. It came to him that its night and day periods must be highly irregular.
When the sun climbed from the waters behind them they were flying still over a boundless waste of waters, but soon they sighted on the horizon ahead the thin green line of land. Sarja slowed as they reached it, took his bearings, and sent the craft flying onward.
They passed over a green coastal plain and then over low hills joined in long chains and mantled by dense and mighty jungles, towering green growths of unfamiliar appearance to Norman. He thought he glimpsed, more than once, huge beastlike forms moving in them. He did see twice in the jungles great clearings where were fair-sized cities of bright-green buildings, a metal tower rising from each. But when he pointed to them Sarja shook his head.
At last, as they passed over another range of hills and came into sight of a third green city with its looming tower, the other pointed, his face alight.
"My city," he said. "Fallas there."
Fellows! Norman's heart beat faster.
They shot closer and lower and he saw that the buildings were obviously green to lend them a certain protective coloration similar to that of the green jungles around them. The tower with its surmounting cage puzzled him though, but before he could ask Sarja concerning it his answer came in a different way. A long metal tube poked slowly out of the cage on the tower's top and sent a hail of force-shells flicking around them.
"They're firing on us!" Norman cried. "This can't be your city!"
"They see our black boat!" Sarja exclaimed. "They think we're Rala raiders and unless we let them know they'll shoot us out of the air! Stand up--wave to them--!"