The sun rose high in the sky as the Esperance returned to the wharf. Davis went ashore and held lengthy conversations with Manila by short-wave radio. The biologists essayed to investigate the squid. La Rubia still attempted to catch fish. All efforts seemed to tend toward frustration.

When Terry walked over to see his victim at close range, he found the biologists balked by the mere huge size of the squid. There were literally tens of tons of flesh to be handled. Squid have no backbone, but a modified internal shell is important to biologists for study. The biologists wanted it. The gills needed to be examined, and their position under the mantle noted, and their filaments counted. The nervous system of the huge creature must have its oddities. But the actual preservation of the squid was out of the question. The mere handling of so large an object was an engineering problem.

Terry consulted the frenziedly swearing CapitÁn Saavedra, who was ready to weep with sheer rage as he contemplated torn nets, and fish he could not capture. Squids were an article of commerce. Terry took the CapitÁn to view this one. His crew would help the biologists get at the scientifically important items, and for reward they would have the rest of the giant—more than they could load upon La Rubia. This would make their voyage profitable, and the CapitÁn would have the opportunity to tell the most stupendous story of his capture and killing of the giant. With the evidence he'd have, people might believe him.

Presently, the crewmen of La Rubia clambered over the monster, huge knives at work under the direction of the men from Manila. There was bitter dispute with the tracking station cook, who objected to the use of his refrigeration space to freeze biological material before it was sent to Manila by helicopter.

In mid-afternoon the Esperance left the lagoon again. The sonar-depth-finder probed the depths delicately. The objects in mid-sea, it appeared, had been rising steadily. Their previous position had averaged twenty-five hundred fathoms deep. They were now less than two thousand fathoms down, and there were many of them. Unfortunately, the Esperance was not a steady enough platform for the instrument. But a fairly accurate calculation was made, and if the unidentified objects continued their ascent at their present rate, they would surface not long after sunrise. Then what?

Increasingly urgent queries came by short-wave, asking for Dr. Morton's explanation of how he had computed the landing place and time of the latest bolide. His accuracy was not disputed. But astronomers and physicists wanted to be able to do it themselves. How had he done it?

Terry came upon him sitting gloomily before a cup of coffee in the tracking station. Davis was there too.

"I wish I hadn't done it," Morton confided. "It's one of those things that shouldn't happen. It's bad enough to have a giant squid to account for. They tell me it's a new species, by the way. Never found or even described before. One of the Pelorus men tells me it's an immature specimen, too. It's not full-grown! What will a grown-up one be like?"

"I have a hunch we'll find out when those submerged giants reach the surface," said Davis unhappily.

Terry said, "The one we killed couldn't get out of the water. I wonder if the adult forms can walk over the land!"

Davis stared. "Should we send Deirdre to safety on the Esperance?"

"Safety?" asked Terry. "On a boat? When a mass of bubbles from undersea could provoke such a turmoil in the water that no ship could stay afloat? That's how one ship disappeared. It might be the Esperance's turn next. Who knows?" Then he added, "There's no limit to the size of a swimming creature!"

A bald-headed member of the tracking station staff walked in. He carried an object of clear plastic. It was a foot and a half long, about six inches in diameter. There was an infinite complexity of metallic parts enclosed in the plastic.

"I caught one of the fishermen making off with this," he said in a flat voice. "It was fastened to one of the squid's shorter arms. The fishermen didn't want to give it up. The skipper claimed it as treasure-trove."

He put it down on the table. Davis, Terry and Morton looked at it. Then Morton shrugged his shoulders, almost up to his ears.

"The intelligent being that made it," said Davis, "apparently came down from the sky in a bolide. That's easier to believe than that a submarine civilization of earthly origin lives down in the depths. But why would anybody prefer the bottom of the sea to—anywhere else on earth? Where would such a creature come from?"

Deirdre walked in and stood by the table, watching Terry's face. The bald-headed man said, "I could believe some pretty strange things, but you can't make me believe that a creature can develop intelligence without plenty of oxygen. There's not much free oxygen at the bottom of the sea."

"But there's something intelligent down there," said Davis doggedly. "If it has to have free oxygen, you've only raised the question of where it gets it. Maybe it brings it."

Deirdre shook her head. "Foam," she said.

The four men stared at her. Then Terry said sharply, "That's it! On the Esperance there's a picture of a huge mass of foam on the sea. A ship dropped right out of sight right into it. Deirdre found the answer! Something down below needs free oxygen. In quantity. Why not get it from the water? What to do with the hydrogen that is left? Let it loose! It'll come to the surface, make a foam-patch...."

Dr. Morton said with a sort of mirthless geniality, "I add a stroke of pure genius! Davis just asked what would be the origin of a creature which preferred the depths of the sea to any other place on earth. What's to be found down there that's missing everywhere else? Cold? No. Moisture? No. Just two things! Darkness and pressure! At the bottom of the Luzon Deep the pressure is over seven tons to the square inch. There's no light—I repeat, none—below three hundred fathoms. Down at the sea-bottom it's black, black, black! Now, where in the universe could there be creatures capable of riding down here in a bolide, and in need of an environment like that?"

Terry shook his head. He remembered seeing a book on the solar planets, in the after-cabin of the Esperance. He hadn't read it. The others on the yacht must have.

"How about Jupiter?" asked Deirdre. "The gravity's four times the earth's, and the atmosphere is thousands of miles thick. The pressure at the surface should be tons to the square inch."

Morton nodded. With the same false geniality he added, "And there'll be no light. Sunlight will never get through that muggy thick atmosphere! So we consider ourselves to be rational beings and guess that the bolides come from Jupiter! But I must admit that the last bolide was headed inward toward the sun, and from the general direction of Jupiter. So-o-o-o, do we warn the world that creatures from Jupiter are descending in space ships and are settling down under water, at a depth of forty-five hundred fathoms? Like hell we do!"

He got up and walked abruptly away.

"I ..." said the bald-headed man, shaking his head incredulously, "will put this gadget away and go back to carve some more squid."

"I'll talk to Manila," said Davis drearily. "Something is coming up from below. There shouldn't be any ships allowed to come this way until we find out what's happening."

Deirdre smiled at Terry, now that they were alone.

"Have you anything very important to do just now?"

He shook his head.

"If the things that are coming up are—space ships, we can't fight them. If they're anything else, they can't very well fight us. If we wanted to attack something at the bottom of the sea we'd have to fumble at the job. We wouldn't know where to begin. So maybe, if a submarine power wants to attack at the surface of the sea, it may find it difficult, too."

He frowned. Deirdre said, "Let's go look at the sea and think things over!"

She very formally took his arm and they walked out. Presently, they stood on the white coral beach on the outer shore, and talked. Terry's mind came back, now and then, to how inadequate his previous guesses about the impending menace had been. It seemed now that the menace must be much worse than he had imagined. But there were many things he wanted to say to Deirdre.

As they talked, they were disturbed. The helicopter, which had left before noon loaded down with biological material for Manila, was approaching again. It landed by the tracking station. Then they were alone again.

When night fell, they were astonished at how quickly time had passed. They went back to the station. The helicopter was on the ground. The biologists had stopped their work, exhausted but very excited by their discovery of a new species of squid, of which an immature specimen measured eighty feet. It had offered extremely interesting phylogenic material for the Cephalopoda in general. The photographs they'd taken were invaluable, from a scientific viewpoint.

The crew of La Rubia had returned to their boat. The Esperance had been out beyond the reef once more. The unidentified objects were still rising. They had risen to less than a thousand fathoms from the surface, well before sundown. At this same rate of rise, they should reach the surface some time after midnight. What would happen after that?

"What will happen depends," said Terry, "on how accurate their information about us is. It depends on their instruments, really. I suspect their ideas about us are weird. I find I haven't any ideas about them."

At dinner, Davis said worriedly, "I talked to Manila. The mine layer that was in the Bay left harbor yesterday. The flattop picked it up by radio and they're both going to come on here tomorrow. I had to talk about the foam. They weren't impressed. The squid does impress them, but the foam—no. I hate," he said indignantly, "to try to convince people of things I couldn't possibly be convinced of myself!"

They talked leisurely. Somebody mentioned La Rubia. It had been more or less expected that her skipper would turn up for drinks and conversation again. But he hadn't. The conversation turned to the plastic objects. They might or might not pick up sounds. It was not likely they'd respond to light. Certainly, complete images would be meaningless to creatures who had evolved in blackness and without a sense of sight. They might respond to pressure-waves, such as are known to be picked up by fish when something struggles in the water, even though man-made instruments have not yet detected them. They might furnish data of a sensory kind that is meaningless to humans, as pictures would be to Jovians. If there were such things....

"Why argue only for Jupiter?" asked Deirdre. "Venus is supposed to be mostly ocean. There could be abyssal life there."

The crew-cuts joined in the argument, but tentatively, because there were many experts present.

Midnight came. The open sea outside the reef showed nothing unusual. The waves glittered palely at their tips. There were little flashings in the water where an occasional surface fish darted. The stars shone. The moon was not yet risen.

Two o'clock came. The Esperance people were divided. Terry and Davis were too apprehensive to sleep. Deirdre'd gone confidently to the yacht to turn in. The crew-cuts slept peacefully, too. Davis said uneasily, "I've got a feeling that the ... objects are at the surface, or very close to it, but that they simply aren't showing themselves. I think they're lying in ambush. The squid that was killed must have had trouble getting into the lagoon. They probably won't try to get the big ones in. They'll wait...."

Terry shook his head.

"We killed that little one—save the mark!—and its death was probably reported in some fashion. So maybe they'll use the big ones on the surface as bait for another kind of weapon. Foam, for example. We know how a ship simply dropped out of sight, as if into a hole."

"I know!" said Davis drearily. "I told the flattop about that. But I don't think they really believe it."

At two-thirty Davis and Terry went down to the yacht. They stood on the deck. They kept watch by mere instinct. There was no activity anywhere. Faint noises were coming from La Rubia. Maybe her crew was repacking the hastily loaded masses of squid-flesh. The last-quarter moon rose at long last, and shone upon the glassy-rippled water of the lagoon. Star-images danced beside its reflection.

A little after three, quite abruptly, the Diesels of La Rubia rumbled and boomed. The dark silhouette of the ship headed across the lagoon toward its opening. Terry swore.

"She lifted her anchor without making a noise," he said angrily. "Her skipper wants to get to Manila with his catch before it spoils! Damnation! I told him not to leave without warning. Anything could be waiting outside!"

He raced for the shore and the outboard motorboat. Davis shouted down the forecastle and pelted after him. Terry had the outboard in the water by the time Davis arrived. He jumped in and pulled the starter. The motor caught.

The outboard went rushing across the water. Its wake was a brilliant bluish luminescence.

The booming of the Diesels grew louder. CapitÁn Saavedra thought he had put over a fast one on los americanos, who had moved the fish from where he regularly captured them in vast quantities and gathered them in a lagoon where his nets tore. They had given him most of a monster squid, true, but they had reserved certain parts for themselves. They were undoubtedly the most valuable parts. So when labor officially ceased at sundown, La Rubia's skipper only pretended to accept the idea. In the last hour his crew had quietly completed loading La Rubia with squid. They'd been carefully silent. They'd lifted anchor without noise. Now La Rubia headed for the lagoon entrance, heavy in the water but with precise information about what coral heads needed to be dodged. She had on board a cargo history had no parallel for. Her skipper expected to be rewarded with fame, as well as cash.

When the outboard motor rushed toward La Rubia, CapitÁn Saavedra zestfully gave his engines full throttle. When the racketing, roaring motorboat arrived beside his ship, and Terry shouted to him to stop, he chuckled and drove on. In fact, he left La Rubia's pilot-house to wave cheerfully at the two men. They frantically ran close and shouted to him above the rat-tat-tatting of their own motor and the rumble of his Diesels.

La Rubia reached the lagoon entrance with the smaller boat close at her side, and Terry still shouting.

But CapitÁn Saavedra did not believe. Maybe he did not understand. Certainly he did not obey. Ocean swells lifted and tossed the motorboat. It became necessary to slow down, for safety. But La Rubia went grandly on, into the open sea.

"We can't force him to stop," said Davis in a despairing voice. "He won't. I only hope we're wrong, and he gets through!"

The outboard stayed where it was, and swells tossed it haphazardly. La Rubia switched on her navigation lights. She drove zestfully to the southward. She sailed on, dwindling in size, as the drone of her Diesels diminished in volume.

Looking back, Terry saw the Esperance approaching from the lagoon, dark figures on her deck. Terry shouted, cries answered him, and the Esperance came to a stop as the motorboat drew alongside.

Terry and Davis scrambled to her deck while one of the crew-cuts led the smaller boat astern and tethered it.

"We're safe enough here," Terry said bitterly, "and since you've come, we can stay and watch if anything happens. If only she keeps on going...."

But La Rubia did not. Her lights showed that she had changed course. She changed course again. Her masthead light began to waver from side to side. She wallowed in such a way that it was clear she was neither on course nor in motion any longer.

Nobody gave orders, but the Esperance's engine roared. The action from this point on became an automatic and quick response to an emergency.

The schooner-yacht plunged ahead at top speed. Terry switched on the recorder and the ultrapowerful sound projector. Davis bent over the searchlight. Two of the crew-cuts readied the bazookas.

Suddenly, a flare went off on La Rubia's deck. Her stubby masts and spars became startlingly bright. Screams came across the waves, even above the growling of the surf and above the noise of the Esperance's engine.

The flare shot through the air. It arched in a high parabola, bright in the sky, and fell into the sea. Another flare was ignited.

The Esperance's searchlight flicked on. A long pencil of light reached across the waves as she raced on. More screamings were heard. Another flare burned. It arched overside. The Esperance plunged on, shouldering aside the heavier waves of open water.

A half-mile. A quarter-mile. La Rubia wallowed crazily, and more shrieks came from her deck. Then the fishing boat seemed to swing. Beyond her, a conical, glistening and utterly horrifying monster emerged, a mere few yards from her rail. Enormous eyes glittered in the searchlight rays. A monstrous tentacle with a row of innumerable sucker-disks reached over the stern of La Rubia.

Another flare swept from the fishing boat's deck in the direction of the giant squid. It fell upon wetted, shining flesh. The monster jerked, and La Rubia was shaken from stem to stern. Hurriedly, Terry pressed the power-feed button, and the sound projector was on. Its effect was instantaneous. The monster began to writhe convulsively. It was gigantic. It was twice, three times the size of the squid captured in the lagoon. Terry heard his own voice cry out, "Bazookas! Use 'em! Use 'em!"

Flaring rocket missiles sped toward the giant. Davis flung one of the hand grenades he'd manufactured. The yacht plunged on toward the clutched, half-sunk fishing boat. The hand grenade exploded against the monster's flesh. Simultaneously, the bazooka-missiles hit their target and flung living, incandescent flame deep into the creature's body. Those flames would melt steel. They bored deeply into the squid, and they were infinitely more damaging than bullets.

The creature leaped from the water, as chunks of its flesh exploded. It was a mountainous horror risen from the sea. As it leaped, it had squirted the inky substance which is the squid's ultimate weapon of defense. But, unlike small squid, this beast of the depths squirted phosphorescent ink.

The beast splashed back into the sea, and the wave of its descent swept over the deck of La Rubia. The fishing boat nearly capsized. But the monster had not escaped the anguish of its wounds. It fought the injured spots as though an enemy still gnawed there. It was a struggling madness in the sea.

The Esperance swung to approach the half-sunken trawler, and Terry kept the searchlight on the turmoil. The beast knew panic. It was wounded, and the abyss is not a place where the weak or wounded can long survive. Its fellows would be coming....

They did. Something enormous moved swiftly under the sea toward the wounded monster. It could be seen by the phosphorescence its motion created, as it approached the surface. There was a jar, a jolt. Some part of it actually touched the Esperance's keel. The huge monster moved ahead, but a trailing tentacle flicked up to what it had touched a moment before.

The ugly tentacle trailed over the yacht's rail. The rail shattered. The forecastle hatch was wiped out. The bowsprit became mere debris which dangled foolishly from the standing rigging.

The Esperance bucked wildly at this fleeting contact. Nick fired a bazooka-shell, but it missed. Holding fast, Davis flung a grenade. It detonated uselessly. It was then that Deirdre screamed.

Terry froze for an instant. There had simply been no time for him to think that Deirdre might be aboard. It was inexcusable, but nothing could be done now.

Tony had been knocked overside by the shock of the contact with the giant, and was swimming desperately trying to follow the yacht and climb back on board. Terry flashed the searchlight about. He found Tony, splashing. The Esperance swung in her own length while Terry kept the searchlight beam focused. More shrieks came from La Rubia. Davis threw a rope and Tony caught it. They hauled him aboard, and the Esperance turned again to pluck away the trawler's crewmen.

There were unbelievable splashings off to port. Terry flung the lightbeam in that direction. It fell upon unimaginable conflict. The monster that had passed under the yacht now battled the wounded squid. They fought on the surface, horribly. A maze of intertwining tentacles glistened in the light, and their revolting bodies appeared now and again as the battered creature fought to protect itself, and the other to devour. Other enormous squids came hurrying to the scene. They flung themselves into the gruesome fight, tearing at the dying monster and at each other. There were still others on the way....

The sea resounded with desperate mooing sounds.

The Esperance bumped against La Rubia. Frantic, hysterically frightened men clambered up from the deck of the sinking trawler to the yacht. As soon as they were aboard they implored their rescuers to head for land, immediately.

"Get 'em all off!" bellowed Terry, in command by simple virtue of having clear ideas of what had to be done. "Get 'em all off!"

The stout skipper of La Rubia jumped over the yacht's rail. Without orders, the yacht's engine bellowed. The Esperance turned toward the shore, which now seemed very far away.

Something splashed to starboard. The sea glowed all around it. Terry poured the pain-sound exactly in that direction. The monster went into convulsions. The yacht swerved away to keep its distance. She raced on, past the spot where the giant flailed its tentacles insanely about. It mooed.

The Esperance raced at full speed toward the island. About a mile ahead, the surf roared and foamed on the coral reef almost awash.

Back at the scene of the battle of monsters, there was a sudden break in the conflict. One of the wounded giants broke free. It may have been the one the Esperance had first attacked; perhaps it was another, which might have been partly devoured while still fighting.

In any case, one of them broke loose and fled, with the hellish pack after it. It is the instinct of squids, if injured, to try to find some submarine cavern in which to hide. The monster dived, and the others pursued it. There was no opening in the reef barrier—not underwater. But there was an opening on the surface. The crippled beast had to find a refuge, or be torn to bits. It may have been guided by instinct, or perhaps the current flowing into or out of the lagoon furnished the clue. In any case, the fleeing creature darted crazily into the channel used by the Esperance for passage. For a little way, it proceeded underwater. Then it grounded itself. Hopelessly.

And the pursuing pack arrived.

The sight from the Esperance's deck was straight out of the worst possible nightmare. Glistening serpentine tentacles writhed and flailed the seas. They tore the swells to froth. The pursuers had flung themselves savagely upon the helpless one. The gap in the reef was closed by the battling giants. They slavered. They gripped. They tore. They rent each other....

Terry saw a tentacle as thick as a barrel which had been haggled half through and dangled futilely as its stump still tried to fight.

And more giants came. Terry shouted, and the Esperance turned. He could see large patches of phosphorescence under the surface. And suddenly, he noticed that a few of them had swerved toward the Esperance. As they approached the sound-horn stung them. They went into convulsive struggling, as the sound played upon them, and they passed the Esperance by.

Davis found Terry beside the sound-weapon's controls watching the sea with desperate intensity.

"Listen," said Davis fiercely, "we're out at sea and we can't get back into the lagoon! We'd better get away from here!"

"Across deep water?" demanded Terry. "That dangerous foam can come up from deep water, but maybe not from shallow water. We've got to stay close to the reef until the flattop comes and bombs these creatures—if it will ever come!"

Davis made a helpless gesture. Terry said crisply, "Get the 'copter to hang over the reef and report on the fighting there. Tell it to report to the flattop. They may not believe us, but they may send a plane anyway. And if the ships come, they'll have to believe about the foam! Tell them to listen for it underwater. They've got sonar gear."

Davis stumbled away. Presently, the dark figure of Nick lowered himself through what had been the forecastle hatch. Davis followed him.

Deirdre came over to Terry.

"Terry ..."

"I'm going to beat in the heads," said Terry, "of those idiots who came after your father and me without throwing you on the wharf first!"

"They'd have wasted precious time," said Deirdre calmly. "I wouldn't have let them. Do you think I want to be ashore when you ..."

There was the faintest of palings of the horizon to the east. Terry said grimly, "I'm going to try to find a passage through the surf, to get you ashore. I'm keeping the Esperance in shallow water—inside the hundred-fathom line—but I don't trust it. Certainly I don't trust a ship to make you safer!"

"It's going to be daybreak soon," she protested. "Then...."

"Then we won't be able to see what goes on underwater," he told her. "Those ... creatures down below are smart!"

There was a racketing, rumbling roar from the island. A light rose above the tree-tops. Presently a parachute-flare lit up. Then there was another, as if the men in the helicopter did not believe what they saw the first time.

"Terry," said Deirdre shakily, "I'm ... glad we found each other, no matter what happens...."

Davis came up from below.

"The flattop's only a few miles away. They're now proceeding at top speed. The mine layer's following. They'll be here by sunrise."

---

Far away to the east, some brightness entered into the paling of the sky. A drab, colorless light spread over the sea. The ocean was a dark, slate blue. Swells flattened abruptly about a quarter-mile away. Terry aimed the sound-weapon and pressed the button. Something gigantic started up, and the top of a huge squid's mantle pierced the surface. The giant leaped convulsively, high above the water, save for trailing tentacles. It was larger than a whale. It fell back into the sea with a loud splash, and moved away quickly.

Color came into the sky. The sun's upper rim appeared. Flecks of gold spread upon the sea.

Far, far away at the horizon a dark speck appeared. As the sun climbed up over the edge of the world, the speck turned golden. There was a mist of smoke above it. A plane took off from the ship. Another plane followed.

Fighter planes flashed toward the island. One of them zoomed sharply, like a bird astonished at something it has seen below. It whirled and came back over that spot. There was the rasping whine of a machine gun. Something like a giant snake reared up and fell back again. And now more planes appeared.

Sunrise was suddenly complete. Terry stared out over the sea. And he could not believe his eyes, accustomed as he was to the highly unlikely, now. Giant squids were afloat at the surface. He saw one here, and another there, and another, and another.... They were emerging by tens, by scores.

"They've been sent up," said Terry very grimly, "by an entity that didn't evolve on the earth. They're ... domesticated, in a way. They're watchdogs for whatever arrives in bolides that fall in the Luzon Deep. They are the reason for the shining circle of sea from which thousands of tons of living fish were drawn down into the abyss. The creatures—the ... ellos who listen to what fish and fishermen say—they keep these things as domestic animals. And they have to feed them. Those mooings were the ... cries of these things waiting to be fed. Try to imagine that, Deirdre! In the blackness of the pit, in the abyss at the bottom of the sea...."

A tentacle broke surface. Terry swung the sound-beam. A mantle reared above the waves. A bazooka-shell hit it. Something huge and stupid and monstrous fought the impalpable thing that hurt it....

Davis approached.

"These," he said absurdly, "aren't the creatures who made the plastic objects. Maybe we ought to try to open communication with their masters. Why should we fight? If we prove we can defend ourselves...."

"I suspect," said Terry, "that all intelligent beings think the same way, intelligently. If we landed on another planet, on some part of that planet that the natives didn't use but we could, it wouldn't be sensible for those natives to welcome us! Trade with us, perhaps. But let us settle down, no!"

There was a bomb explosion out at sea. A plane had dropped a hundred-pound bomb on a monster at the surface. The flattop was now distinct. Golden, almost horizontal sunlight struck upon it. Off to the west a plane dived steeply, something dropped from it, and the plane levelled off. A three-hundred-foot fountain erupted from the surface. Then there came absolute proof that intelligence lay behind all this. It was not human intelligence, to be sure. Men are tool-using creatures nowadays. They imagine robots for fighting, and nowadays they make them, but many centuries ago men ceased to try to use animals as combatants in war.

The creatures under the sea had not. They'd send up giant squids to do battle with men, as men once sent elephants against the Macedonian army. It was naÏve. But the generals, the tacticians, the strategists of the Deep did not remain wedded to the one weapon. Already, they saw that beasts could be fought by men. So their instruments of battle changed. Doubtless, orders were given, and five miles under the sea something—something men could not have duplicated—began the transformation of seawater into gas, in quantities past imagining. Tiny, tiny bubbles were produced by some unguessable engine, and rose toward the surface, in a steady stream. At the bottom they were under a pressure of tons to the square inch. But the pressure lessened as they rose, and as they rose they swelled. A bubble which was pinhead-size at the sea-bed grew to be the size of a basketball a half-mile up, and would have been the size of a house a mile up, except that then it separated into smaller ones. They rose and rose and expanded and separated. Five miles up from their origin, at little more than atmospheric pressure, they made a rising column of insubstantiality. At the surface they became foam. But under the foam there was more foam, and under that still more. A ship sailing from normal ocean water into such airy stuff would drop like a stone into the miles-long cone of semi-nothingness. Nothing solid could float there. Nothing substantial could rest its weight upon such rushing thistledown.

And the first of the bubble-weapons appeared at the surface in the form of a patch of foam. Its source—and hence the place of its appearance—could be moved. It could be shifted under any ship, though there would be a time-interval, always, before the foam at the surface was exactly above the gas-generating engine below. It could be moved to anticipate the movements of a ship. But there was always that time-lag.

The Esperance headed back toward the heap of monsters at the break in the reef. Other giant squids emerged and joined the pack. A plane came over and bombed it. The Esperance turned away. The mine layer from Manila appeared at the horizon. The flattop made a sudden violent turn, and more foam appeared upon the water. It curled and writhed and piled up to be ten—twenty—thirty yards in height.

The flattop fired a shell into it. There was a gigantic flash and flame, and for an instant there was no foam, but only peculiarly pock-marked ocean surface, instantly covered by more foam which piled up as before.

"Gas," said Terry grimly. "Hydrogen. You guessed right, Deirdre!"

Now the flattop shot off plane after plane, as if they were projectiles. They swung in the air and flew low to drop bombs in the now wabbling, moving, sweeping patch of white stuff. It was a huge discoloration of the ocean surface. It was almost in diameter as the flattop's length. Now the carrier dodged it warily.

There were dull concussions everywhere. Giant squids writhed in death-agonies. White foam-patches appeared here and there—but somehow haphazardly—as if fumbling for the ships. One patch swept close to La Rubia, and that small derelict seemed to tremble. And then the fishing boat touched the very edge of the white stuff, and was engulfed in it. She vanished instantly, as if she had fallen into a hole in the sea. When the foam-patch passed on, the sea was empty.

The effect of the foam, actually, was that of a gigantic, slavering, blind gullet straining to devour. It moved erratically over the surface. Terry called to Deirdre, "Have Nick tell the flattop that the foam only comes up from deep water. If they can get inside the hundred-fathom curve they're safe! Maybe even five hundred. Maybe more. But the foam only comes up from deep water!"

The mine layer came on from the horizon at topmost speed. Apparently, they had received warning from the carrier, because the ship suddenly began to zig-zag. The carrier itself adopted the unpredictable change-of-course system which had been originally designed to frustrate submarines lying in wait. Both ships adopted it just in time. A ravening area of foam appeared directly before the mine layer's bow just as she turned aside. The mine layer dumped a mine. Terry saw it go overboard. But it would have five miles to sink before it hit bottom.

Terry called Davis and jerkily explained that the mines would have to be armed when they went overboard—set so that they would explode when they hit bottom. He explained that depth-bombs might be useful against squids, but if they went off at a fixed depth they would be harmless against the enemy which deployed the squids.

The carrier, in the middle of a ninety-degree zig-zag turn, found her bow projecting into a foam-patch. The bow sank deep. The carrier's propellers were out of the water as her bow pointed downward. Had the foam stayed still for two seconds, the carrier would have slid into the column of gigantic ascending bubbles and plunged to destruction. But the foam swerved sidewise.

The carrier escaped, and was infinitely cautious after that. She made short, swift, unpredictable dashes this way and that.... Her anti-aircraft guns rumbled and rattled at things upon the surface. Presently, her depth-finder discovered an underwater extension of the island's mountain-foundation, and the ship took refuge where the water was less than a hundred fathoms deep. There she lay, shooting off planes and retrieving them, her guns flashing at whatever targets appeared.

Twice, as it happened, snaky, monstrous arms flung themselves up and heaved at the flattop as if the giant squids hoped to overturn even an aircraft carrier by their weight. But those arms were blasted to nothingness. The only damage they did was that a twenty-foot section of tentacle—writhing independently on the flight-deck—broke the landing-gear of a returning plane which collided with it.

The mine layer ploughed across the sea. From time to time she heaved something overboard. Nothing seemed to happen. But each mine was, nevertheless, so adjusted that it could explode any time it touched something underwater. They did not allow the usual time so that the mine layer could get away. The mine layer had ample time, because the mines had to go slowly spinning down five long miles to the bottom of the Luzon Deep.

Twenty mines went down before the first one detonated. The concussion was felt on the Esperance, twenty-seven thousand feet up and in shallow water. Then another, and another, and another. The mine layer continued to sow her destructive seed. Far behind her, a monstrous spouting of gas and spume rose up hundreds of feet. There was another concussion, and another....

The Esperance quivered, and Terry said grimly to Deirdre, "We set off five pounds of explosive down the Deep, and the bathyscaphe returned all smashed. What will the creature do now? I wish we could get some mines down to the bottom there!"

Davis came up, beaming—but shaking.

"The carrier's sending some planes down to drop eggs at the spot where the fish were dragged down!" he said zestfully.

Gigantic, terrifying masses of gas leaped skyward where the gases released by the exploding mines finally reached the surface. The mine layer zig-zagged, and dropped a mine. She zig-zagged again, and dropped another. Presently, she took refuge beside the carrier. The Esperance drove over and came to a stop between the two armed vessels. Someone shouted down by megaphone from the carrier's deck, "What happened to you? What hit your bowsprit?"

Terry shouted back, "You shot those beasts. We've been wrestling with 'em!"

An enormous eruption of gas.... Then the underwater ear began to emit an unprecedented sound. It was a rushing sound, but it was only vaguely like the noise of whatever had come up from the depths last Tuesday night. This was powerful beyond imagining.

"Something's coming up!" roared Terry. "Better alert for a real fight now!"

Deirdre said with a little gasp, "The real creatures are coming up! Terry! The ... things that come in the bolides...."

He said savagely, "They've been shaken up badly by the concussions underwater. They resented five pounds of explosive! There's been four hundred pounds in every mine! If they try to fight after what they've taken down below...."

The rushing sound from underwater was a loud, throbbing hum which had no relationship with the humming sound that drove fish. Two spoutings of gas from mine-explosions shot up. There were more concussions in the water.

Then something broke surface. It was huge, and looked like a rocket. It leaped. No, it dashed upward, toward the sky. It flashed skyward, accelerating as it rose. Something else broke the surface and headed for the heavens. This one was globular.

There were dull concussions coming from far underwater, and more rockets broke surface and shot skyward.

Anti-aircraft guns were fired. Shell-bursts came close, but not close enough. Not less than twenty enormous rockets leaped out of the water and shot up toward the sky. Some observers claimed there were more than thirty. Down to southward, where the bathyscaphe had been crushed, the planes that were dropping mines reported that four other objects broke loose from the ocean and fled for empty space at speeds too great to be estimated.

Terry looked suddenly astonished.

"But ... of course!" he told Deirdre. "When you need high pressure, of course you've got a weakness. You can't take concussions! Anything underwater is completely vulnerable to bombs! Whatever was down there has found out that the natives—we aborigines—have a weapon they can't face. Primitive stuff. Explosives! Chemical explosives! And creatures that can travel between planets and undoubtedly have atomic power and—who knows what else—can't fight back if we drop submarine mines on them!"

A last object broke surface and hurtled skyward. Behind it, deep, deep down, there was a titanic explosion.

"Ah!" said Terry. "That was a time-bomb! They've gone home for good!"

---

A task force of a private yacht, a fishing boat, a satellite-tracking station, an airplane carrier and a mine layer had driven off an invasion of earth. But the public could not be told that the earth had been invaded. The people who had been involved in this secret adventure had to be satisfied with the realization that they had saved mankind.

After a jubilant dinner Terry and Deirdre sat in the veranda.

Davis came out. He blinked at the night.

"Deirdre? Terry?"

"Here," said Terry.

Davis joined them. They had drawn apart a little.

"Good news by short-wave," said Davis. "Those rockets were picked up by radar. They divided into two groups. One headed sunward. The other headed for deep space. My guess is Venus for one group and Jupiter for the other. They couldn't have come from Mars. But they've gone home. Both groups."

Terry paused, and then said wryly, "Two races! Some of the bolides were bullet-shaped and some were globular. That figures. But two races capable of space travel and both in our own solar system!"

Davis grimaced. "We've been talking about it. Our guess is that the Venus race developed in deep water, and therefore at high pressure. And anything that developed on the solid surface of Jupiter would also be accustomed to extremely high pressure."

Terry nodded. He was not exactly absorbed in what Davis had to say. But he said suddenly, "I make a guess. They didn't want to start a colony here. The sea-bottom here is too cold to be comfortable for the beings from Venus, and far too hot to suit those from Jupiter. But both needed terrific pressure. In order to keep contact with each other, in order to do business, they could have set up a trading post here. To meet and trade. Neither one could take over the earth. When you think of it, we couldn't take over Venus or Jupiter! Maybe that's the answer!"

"Eh?" said Davis.

"We won't have to fight as planets," said Terry, "when we have space-ships like they do. We couldn't gain anything by fighting. All we can gain by is trade. They'll be pleased. It must have been horribly inconvenient to have to set up a trading post here on earth. There were always the natives, you know. Lately, they've noticed that we've been getting restless. We have been. I imagine that now they'll wait for us to make space-ships and start up interplanetary trade."

Davis said, "Very true. There's going to be the devil of a mess, though. Morton will still have to explain the accuracy of his prediction about the bolides' landings. I suspect he'll be censured for assuming anything as unlikely as the truth has turned out to be."

Terry did not answer. Deirdre was saying something, and he did not hear at all.

"There are still loose ends," added Davis. "For instance, how do you suppose they controlled those squids down below? What did they use for eyesight? How the devil would Jovians and Venusians agree on a meeting place in our oceans?"

Terry answered what Deirdre'd said. She smiled at him. They'd forgotten that Davis was there.