The edge of the sun touched the horizon and sank below it, out of sight. There were magnificent tints in the sky, and the gently rippling harbor water reflected them in innumerable swirlings of color. The Esperance swayed very slightly and very gracefully on the low swells. In minutes two of the dungareed members of the ship's company got the anchor up with professional efficiency. One of them went below, and the Esperance's engine began to rumble. Davis casually took the wheel, and the small yacht began to move toward the open sea while Nick played a salt-water hose on the anchor before lashing it fast. The brief twilight of the tropics transformed itself swiftly into night. Lights winked and glittered ashore and on the water.

Terry felt more than a little absurd. The girl said pleasantly, at his side, "My name's Deirdre, in case you don't know."

"Mine's Terry, but you do know."

"Naturally!" she said briskly. "I should explain that I'm the ship's cook, and the boys forward aren't professional sailors, and my father isn't—"

"Isn't in this business for money," said Terry. "It's strictly for something else. And I don't think it's buried treasure or anything like that."

"Nothing so sensible," she agreed. "Now, if you want to join a watch, you'll do it. If you don't, you won't. The port cabin, the little one, is yours. You are our guest. If you want anything, ask for it. I'm going below to cook dinner."

She left him. He surveyed the deck again, and presently went back to where Davis sat nonchalantly by the Esperance's wheel. Davis nodded.

"Now that you've, well, joined up," he said meditatively, "I've been trying to think how to, well, justify all the mystery. Part of it was Deirdre's idea. She thought it would make our proposition more interesting, so you'd be more likely to take it up. But when I think about explaining, I bog down immediately."

Terry sat down. The Esperance drove on. Her bow lifted and dipped and lifted and dipped. The water was no longer nearly smooth. There was the beginning of a land breeze.

"There's La Rubia," said Davis uncomfortably. "You outfitted her with underwater ears and a radar, at least. Was there anything else?"

"No," said Terry curtly. "Nothing else."

"She catches the devil of a lot of fish," said Davis. He frowned. "Some of them you might call very queer fish. You haven't heard anything about that?"

"No," said Terry. "Nothing."

"I think, then," said Davis, "that I'd better not expose myself to scorn. I'd like to be able to read her skipper's mind, though. But it's possible he simply thinks he's lucky. And it's possible he's right."

Terry waited. Davis puffed on his pipe. Then he said abruptly, "Anyhow you're a good man at making gadgets. We'll let it go at that, for the time being."

The sea became less and less smooth. There were little slapping sounds of waves against the yacht's bow. The muted rumble of her engine was not intrusive. The breeze increased. Davis gave a definite impression of having said all he intended to say for the time being. Terry stirred.

"You want me to build a gadget," he said. "To drive fish. Would you want to give me some details?"

Davis considered. A few drops of spray came over the Esperance's side.

"N-o-o-o," said Davis. "Not just yet. There's a possibility it will fit in. I'd like you to make one, and maybe it will fit in somewhere. But La Rubia's the best angle we've got so far. There is one gadget I'd give a lot to have! You know, a depth-finder. It sends a pulse of sound down to the bottom and times the echo coming back. Very much like radar, in a way. Both send out a pulse and time its return."

Terry nodded. There was no mystery about depth-finders or radars.

"We've got a depth-finder on board," said Davis. "If I sail a straight course and keep the depth-finder running, I can make a profile of the sea bottom under me. If I had a row of ships doing the same thing, we could get profiles and have a relief map of the bottom."

"That's right," agreed Terry.

"What I'd give a lot for," said Davis, "would be a depth-finder that would send spot-pulses, like radar does. Aimed sound-pulses. And an arrangement made so it could scan the ocean bottom like radar scans the sky. One boat could make a graph of the bottom in depths and heights, mapping even hummocks and hills underwater. Could something like that be done?"

"Probably," Terry told him. "It might take a good deal of doing, though."

"I wish you'd think about it," said Davis. "I know a place where I'd like to use such a thing. It's in the Luzon Deep. I really would like to have a detailed picture of the bottom at a certain spot there!"

Terry said nothing. He'd been made angry, then mollified, and now he felt tempted to grow angry again. There was nothing definite in what was wanted of him, after elaborate machinations to get him aboard the Esperance. He was disappointed.

"Good breeze," said Davis in a different voice. "We might as well hoist sail and cut off the engine. Take the wheel?"

Terry took the wheel. Davis went forward. Four dungareed figures came up out of the forecastle. The sails went up and filled. The engine stopped. The motion of the boat changed. More spray came aboard, but the movement was steadier. Davis came back and took the wheel once more.

"I think," he said, "that we're acting in a way to—hm—be annoying. I ought to lay my cards on the table. But I can't. For one thing, I haven't drawn a full hand yet. For another, there are some things you'll have to find out for yourself, in a situation like this."

"Such as—"

"Well," said Davis with a sudden dogged air, "take those orejas de ellos, for an example. Ellos are supposed to be some sort of beings at the bottom of the sea who listen to fish and fishermen. It's a superstition pure and simple. Suppose I said I was investigating the possibility that there were such—beings. You'd think I was crazy, wouldn't you?"

Terry shrugged.

"What I am interested in," said Davis, "has enough credit behind it for me to get some pretty rare electronic parts from the flattop in harbor back yonder. Nick called them by short-wave, they sent the parts ashore and gave them to Deirdre, and she brought them out to you."

Terry blinked. Then he realized. Of course, that was where just about any imaginable component for electronic devices would be found—in the electronics stores of a flattop! They needed to have such things at hand. They'd carry them in store. Davis said drily, "They wouldn't supply parts to a civilian who was investigating imaginary gods or devils. So what I'm bothered with isn't a superstition. Right?"

"Y-yes," agreed Terry.

It was true. The Navy would not stretch regulations for a crackpot civilian. It was not likely, either, that Horta would have implied so definitely that the Philippine Government wanted somebody with Terry's qualifications to go for a cruise on the Esperance.

Deirdre put her head up through the after-cabin hatch.

"Dinner is served," she said cheerfully.

"The wheel," said Davis to Terry.

He went forward. All four of the non-professional seamen came with him when he returned.

"This is the rest of the gang," said Davis. "You met Nick. The others are Tony Drake, Jug Bell, and Doug Holmes." He made an embracing gesture as they shook hands in turn. "Harvard, Princeton, Yale—and Nick's M.I.T. It's your turn at the wheel, Tony."

One of the four took over. The others filed below after Davis and Terry. Terry was silent. Davis had wanted to show that he was being informative, and yet he'd said exactly nothing about the interests or the purpose of the Esperance's complement.

Dinner in the after-cabin was almost as confusing to Terry. Seen at close range across a table, the four dungareed young men could not possibly be anything but college undergraduates. They were respectful to Davis as an older man and they tended to be a little cagey about Terry, because he was slightly older than themselves but not an honorary contemporary. They plainly regarded Deirdre with the warmest possible approval.

Conversation began, at first cryptic but suddenly only preposterous. There was an argument about the supposed intelligence of porpoises, based on recent studies of their brain structure. Tony observed profoundly that without an opposable thumb intelligence could not lead to artefacts, and hence no culture and no great effective intelligence was possible. Jug denied the meaningfulness of brain structure as an indication of intellect. Intellect would be useless to a creature which could neither make nor use a tool. Doug argued hotly that the point was absurd. He pointed to spastic children once rated as morons but actually having high I.Q.'s. They had intellects, though they had been useless because of their inability to communicate. But Nick asserted that without tools they'd have nothing to talk about but food, danger, and who went where with whom for what. All of which, he observed, needed no brains.

Davis listened amusedly. Deirdre threw in the suggestion that without hands or tools an intelligent creature could compose poetry, and Jug protested that that was nothing to use a brain for—and the talk turned into a violent argument about poetry. Doug insisted vehemently that the finest possible intellects were required for the composition and appreciation of true poetry. Then Davis said, "Tony's still at the wheel."

The argument died down and the crew-cuts devoted themselves to eating, so one of them could get through and relieve him.

Afterward, Davis settled down below to a delicate short-wave tuning process to get music from an improbable distance. Deirdre served Tony his meal and talked with him while he ate it. Terry went abovedecks and paced back and forth as the Esperance sailed on through the night.

He couldn't make out anything at all about the crew or the purpose behind the Esperance's chosen task and purpose. He felt dubious about the whole business. Like most technically-minded men, he could become absorbed in a problem, especially if it was a device difficult to design or a design that somehow didn't work. Such things fascinated him. But the Esperance's crew was not concerned with a problem like that. There was no pattern in their talk or behavior to match the way a technical mind would go about finding a solution. The problem was bafflingly vague, yet there was one.

La Rubia was an element in it. Possibly Davis' wistful mention of a partial map of the bottom of the Luzon Deep fitted in somewhere. Davis had spoken of orejas de ellos with some familiarity, but certainly no Navy ship would cooperate in the investigation of a fisherman's superstition in which even fishermen didn't believe any longer. The Philippine fishing fleet was modern and efficient. Fishermen used submarine ears without superstitious fears, and if they referred to imaginary ellos it was as an American would say "knock on wood," with no actual belief that it meant anything.

Whatever the Esperance's purpose was, there was nothing mystical about it—not if a flattop parted with rare and expensive specialized vacuum tubes to try to help, and the police department of Manila urged Terry tactfully—through Horta—to join the yacht, and no less than a Navy Captain had named him as someone to be recruited.

Deirdre came abovedecks and replaced Tony at the wheel. The Esperance sailed on. A last-quarter moon was now shining low on the eastern horizon. It seemed larger and nearer to the earth than when seen from more temperate climes. The wake of the yacht glowed in the moonlight.

The wide expanse of canvas made stark contrast between its moonlit top and its shadow on the deck. The only illumination on the ship was the binnacle lights and the red and green running lights. Deirdre kept the Esperance on course.

Terry went up to where she sat, beside the wheel.

"I've been making guesses," he told her. "Your father.... I believe that his curiosity has been aroused by something, and he's resolved to track it down. I strongly suspect that at some time or another he's gotten bored with making money and decided to have some fun."

Deirdre nodded.

"Very good! Almost completely true. But what he's interested in is a good deal more important than fun."

Terry nodded in his turn.

"I suspected that too. And it's rather likely that you've got a volunteer crew instead of a professional one because these young men consider it a fascinating adventure into the absurd, and because they'll keep their mouths shut if something turns out to be classified information."

"My father's doing this strictly on his own!" said Deirdre quickly. "There's nothing official about it. There isn't any classified information about it. This is a private affair from the beginning!"

"But in the end it may turn out to be something else," said Terry.

"Y-yes. We don't know, though. It's impossible to know! It's—ridiculous!"

"And my explanation for your being so mysterious with me is that you and your father insist that I find out everything for myself because I'd think it foolish if you told me."

Deirdre did not answer for a moment. There was a movement behind Terry, and Davis came on deck.

"That was good music!" he said pleasedly. "You missed some very interesting sounds, Deirdre! You too, Holt."

"He's decided," said Deirdre, "that we're a little bit ashamed of our enterprise and won't tell him about it for fear he'll simply laugh at us."

Terry protested, "Not at all! Nothing like that!"

"When some forty-odd people have been killed by something inexplicable at one time that we know of," said Davis, "—and we don't know how many others have been killed at other times, or may be killed by it in the future—I don't think that's a laughing matter."

He surveyed what should be the direction of the land. A light showed there and vanished, then came on again and vanished. A minute later it showed and disappeared, then came on again twice. It was very far away. Davis said in a different tone, "We can change course now, Deirdre. You know the new one."

The Esperance's bowsprit forsook the star at which it had been aiming. It swung to another. Davis moved about, adjusting the sheets alone. On the new heading the yacht heeled over a little more and the water rushing past her hull had a different sound. The sky seemed larger and more remote than it ever appears from a city. The yacht's wake streamed behind her in a trail of bluish brightness. Even the moon was strange. It had the cold enormousness of something very near and menacing. It looked as close as when seen through a telescope of moderate power.

The Esperance seemed very lonely on the immense waste of waters.

Next morning, of course, the sense of loneliness was gone. There was neither land nor any ship in sight, but gulls fluttered and squawked overhead, and the waves seemed to leap and gambol in the sunshine. Just before the foremast a metal plate in the decking had been lifted up, and a new, stubby, extensible mast rose almost as high as the crosstrees. A tiny basket-like object rotated monotonously at its upper end. It was a radar-bowl, and somehow it was not unusual, except in the manner in which it was mounted. Yet, such a collapsible radar mast was reasonable on a sailing yacht with many lines aloft that could be fouled. Anyhow, the radar was concerned with human affairs, and so it was company.

The housekeeping work on the boat was in progress. Doug and Jug scrubbed the deck. The other crew-cuts gave signs of industry from time to time, appearing and vanishing. Davis smoked tranquilly at the wheel. Terry felt useless, as well as puzzled.

"Can I do anything?" he asked awkwardly.

"You're your own boss," said Davis.

"Then I might as well see what can be done about that submarine noisemaker."

"If you feel like it," said Davis, "fine!"

But he did not urge. Terry waited a moment. There was a sort of contagion of purposefulness in this eccentric small group on the Esperance. They had something they were trying to do, and it seemed important to them. But Terry was an outsider and would remain one until he became active in their joint effort.

He got out his equipment and materials and spread them out. There was no need to build a recorder, since there was one among the supplies. The rest wouldn't be unduly difficult. He established a working space and set systematically to work. The task he'd accepted was essentially simple. A submarine ear was to pick up underwater sounds. He had to modify a microphone and enclose it in a water-tight housing, with certain special features that would make it highly directional. The recorder would take the pick-up and register it on magnetic tape, while playing it for simultaneous listening. Then he had to assemble a machine for playing back the taped sounds under water. That required a unit for a submarine horn, to broadcast the amplified sound. It isn't difficult to make a sound under water. One can knock two stones together under the surface and a swimmer can hear it a mile or more away. But a horn to reproduce specific sounds is more difficult to build. It needs extra power. A sound-truck in a city, competing with all the traffic noises, will turn no more than fifteen watts of electricity into noise. But much more power would be needed to produce a similar volume under water.

Terry modified the mike into a submarine ear—an orejas de ellos. Then he began to assemble an audio amplifier to build up the volume of the sounds already taped for re-use under the sea. He had the parts. It was mostly just finicky labor. He sat cross-legged in the sunshine, not far from the Esperance's unusual winch.

Nick came up from below and went aft. He spoke to Davis. Terry couldn't hear what was said, but Davis gave orders.

The Esperance heeled over; away, away over. The four crew-cuts adjusted the sheets for maximum effect of the sails on the new direction of motion. The yacht seemed to tear through the water like a racing boat. Terry had to rescue some of his smaller parts which started for the scuppers. He looked up. Deirdre said cheerfully, "Our radar picked up a boat that's probably La Rubia on the way back to Manila. We don't want her to see us."

Terry blinked.

"Why?"

"We're going to take a look at the spot where we think she catches her fish," said Deirdre. "It's strange enough that she catches so many, but what's even stranger is the kind of fish she catches at times."

"How?"

Deirdre shrugged. Then she said irrelevantly, "La Rubia's skipper would like to have the only radar in the world, as you've reason to know, and he doesn't think of radars, except his own and possible competitors. But there are lots of others. We're probably a blip on somebody's radar-screen right now. In fact, we're supposed to be. So when my father got interested in La Rubia and her—catches, he was able to have somebody notice where she goes every time she slips away from the fishing fleet. And so he was told. It was all quite unofficial, of course."

Terry bent over his task again while the Esperance sped along over the off-shore swells. There was no land in sight anywhere. An albatross glided overhead for a time, as if inspecting the Esperance as a possible source of food. When Terry looked for it later it was gone. Once there was a flurry in many wave-flanks, and a small school of flying fish darted out of the sea with hazy, beating fins, and dived back into the sea many yards from where they started.

But nothing of any consequence happened anywhere. Terry fitted and soldered and tested. By noon he had a rather powerful audio amplifying unit, set up to magnify any sound the tape-recorder fed into it. Deirdre prepared a meal. The galley of the Esperance was admirably supplied with all kinds of food. After the noon meal the yacht changed course again to a line which would intersect her original morning course at some point.

Terry found himself fuming. He'd set to work to make something that Davis apparently wanted, but his most elementary questions still ran against a blank refusal to answer. Both Davis and Deirdre had spoken of oddities in the catches of La Rubia. There could not possibly be any reason for them to refuse to tell him what they were. Terry worked himself into irritability, recalling how he volunteered to come on the Esperance but not thinking that he would be treated as someone who wasn't allowed to know what everybody else aboard most certainly did.

In the afternoon there was guitar music down in the forecastle, and Doug came out and settled himself on the bowsprit with a book of poetry. Presently Nick sat down close by Terry and watched interestedly as he put mysterious-looking electronic elements together into incomprehensible groups. When he had finished, Terry did not admire his handiwork. The noisemaking unit came last. The electrical part had to be enclosed, water-tight, with a diaphragm exposed to the water on one side and its working parts protected from all moisture on the other. The device looked cobbled, but it worked, and made monstrous sounds in the air.

Now he plugged the submarine ear into the recorder. He dropped it overside and taped the random noises of the sea: the washings of sea water against the Esperance's hull, frequent splashings, and very faint, chirping noises from who-knew-what.

"Watch the volume, will you?" Terry pointed out the Indication that should not be exceeded. Nick nodded. "I'm going to whack the paddle overside and see what we get in the way of noise."

Nick hesitated. Then he said uneasily, "Wait a minute."

He went aft to Davis, apparently somnolent at the wheel. Deirdre joined the two of them in a seemingly very serious discussion. Then she walked over to Terry.

"I hate to say it," she told him with evident concern, "but my father thinks it would be wiser to try out the paddle in shallow water. Do you mind?"

"Yes," snapped Terry. "I do mind, since I'm not allowed to know the reason for that or anything else."

He put away his tools and the unused parts. He pointed to the machines he had already built.

"This is what your father wanted, I think. After it's tested I'll ask you to put me ashore."

He went below, where he fretted to himself. But no one came, either to inform him of Davis' reasons, or to tell him to do as he pleased. He felt like a child who isn't allowed to play with other children; who is arbitrarily excluded from the purpose and the excitement of his fellows. Thinking in such terms did not make him feel any better. His irritation increased. The Esperance was engaged in an enterprise that these people considered very much worth doing. He'd joined them to accomplish it, and they wouldn't tell him what it was. He hadn't the temperament to be content with just following blindly. And somehow the fact that Deirdre was aboard and a participant in the secret made his exclusion an insult.

He felt about Deirdre that urgent concern that a man may feel about one or two, or at most three girls during his whole lifetime. It wasn't a romantic interest, at this stage, but he wanted to look well in her eyes, and he was enormously interested in anything she said and did. If he left the Esperance and ceased to know her, he knew he'd be nagged at by the feeling that he'd made a very bad mistake. He didn't want to stop knowing her. But he refused to be patronized.

He saw an open book on the after-cabin table and glanced restlessly at it. There were three or four photographs and a newspaper clipping stuck into its pages. The book itself dealt with physics at post-graduate levels—which meant that it included a good deal about electronics.

Still fuming, Terry glanced at the pictures. The first was of a spherical object made of transparent plastic and probably of small size. It had a number of metallic elements clearly visible through the transparent case. It looked as if it might be an electronic device itself, but there was no sign of lead-in contacts, and the parts inside made no sense at all. The second and third photographs were of a similar yet slightly different object. The fourth photograph was a picture of what looked like ocean water, taken from a plane. The horizon showed in one corner. The center of the picture was an irregularly-shaped mass of white. On close examination it appeared to be foam. But it looked as if it were piled up in masses above the surface. If the water around it was ocean—and it was—and the visible crest-lines were of waves—and they were—that heap of foam must have been hundreds of yards in diameter and piled many feet high on the surface. Foam does not form in such masses in the open sea. It would not last if it did.

On the margin of this picture a date had been inked—three days before—and a position in degrees of latitude and longitude.

Terry turned to the chart rack. He pulled out a chart and looked up the position. Someone had made a pencil-dot there. It was close to Thrawn Island, on the very brink of the Luzon Deep, that incredible submarine chasm in which the entire Himalayan chain could be sunk without showing a single pinnacle above the surface.

He went back to the clipping. It was dated Manila, two years earlier. It was an obviously skeptical article on a report made by the crewmen of a sailing ship that stopped by Manila. Sailing ships are rare enough in modern times. This ship reported that she had sighted another of her own kind at sea. The two ships altered course to speak to each other. And the one which came into Manila declared that when the other vessel was no more than two miles away, white foam suddenly appeared on the sea just in front of her. A geyser of unsubstantial white stuff spouted up and spread, shooting up about thirty feet on the water. The bow of the other sailing ship entered the foam patch. And suddenly her bow tilted downward, her masts swayed forward, and the entire ship vanished into the white stuff, exactly as if she had sailed over a precipice. She did not sink. She dropped. She "fell" under water—under the foam—her sails still spread. One instant she sailed proudly. The next instant she was gone.

The position of such an incredible happening was roughly given. It was almost exactly the same as the position written on the photograph of foam taken from the air. At the margin of the Luzon Deep.

Terry found that his indignation had evaporated. The reason for it still remained, but now he wanted to know more about this happening and about the spheres of plastic with those deftly designed but enigmatic inclusions. The plastic objects had a purpose. He wanted to know what. And the news clipping....

Having announced crossly that he would ask to be set ashore as soon as the fish-driving unit was tested, he was ashamed to take it back. He stayed below, now angry at himself again. Nobody came below. Deirdre did not descend to cook. Night fell. Well after nightfall he heard movements on deck, and presently a voice which sounded oddly distant. The Esperance's course changed abruptly. The quality of her motion altered once more.

He went abovedecks. Twilight was long over, but the moon was not yet up. Here and there a wave-tip frothed, and blue luminescence appeared. Here and there a streak of dim blue light could be seen under water, where some fish darted. But those dartings were rare. Despite the yacht's shining wake and the curling wave-tips, the sea was darker than usual.

Nick's voice came from aloft, faint and eerie and seeming to come from the stars.

"... farther to port.... Two points ..."

Terry could see the masthead weaving and swaying against the stars, with a small dark silhouette clinging to it: Nick. The yacht began to swing. On one bearing she pounded heavily. The seas could hit her squarely, and they did. Figures moved swiftly about the deck, loosening sheets or tightening them. Nick's voice again, from overhead.

"Stea-a-a-dy!"

The Esperance ceased to turn. Rushing, pounding water sprayed in the air. The waves splashed upon the hull of the yacht, which was sweeping along on a quartering wind.

For a while no one talked. Tony stood at the wheel, with Davis nearby, by the binnacle light. Terry could see Davis glancing into the binnacle, then gazing at the horizon ahead, and then aloft, where Nick seemed to swing among low-hanging stars.

"Ri-i-i-ght!" he called from high overhead. "Steady as she goes."

The Esperance sailed on, over the surging seas. Waves came out of nowhere, leaped beside the yacht and then went by—to nowhere. It was hard to believe that the yacht actually moved forward. She seemed to stay perpetually in the one spot. But there was a winding, sinuous wake, and there was froth under her forefoot.

Then a vague brightness appeared on the sea, at the limit of vision. It spread out more widely as the Esperance approached. Presently it was clearly visible.

Dead ahead, the beam of the headlight suddenly revealed an incredible spectacle. Until then there had been just a few flashes in the water, where some fish darted away from the yacht's bulk. But here the entire surface of the water shone with thousands and thousands of fish. They were packed in a sharply delimited circle about a mile wide. When the Esperance got close enough, she hauled up into the wind to look.

From a spot fifty yards ahead, the sea was alive with a million frantic dartings of swimming things. They were crowded, packed almost fin-to-fin. And it was not a surface phenomenon only. From the yacht's deck the streaks of light were visible deep down, as far as the clear water would let them be seen. They formed a column of glittering chaos. The vast circle, to an indefinite depth, was packed solid with agitated fish. At that edge of brightness the thronging creatures were splashing in a mad frenzy. Solid shining shapes leaped crazily from the water. Some leaped again and again, until they reached the spot where the flashes were thickest, and got lost in the multitude of their fellows. A few escaped to the darker surrounding sea. They seemed to run away in stark terror. But those were only a few. The greatest mass of fish milled crazily inside the circle. There were even porpoises, darting about as if frightened beyond all normal behavior, not even trying to feed on the equally fear-maddened creatures all about them.

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