Another map spread out and this time pinned down with small stones on beach gravel.

"Here, here, and here—" Ashe's finger indicated the points marked in a pattern which flared out from three sides of Finger Island. Each marked a set of three undersea depressions in perfect alliance with the land which, according to the galactic map, had once been a cape on a much larger land mass. Though the Terrans had found the ruins, if those saucers in the sea could be so termed, the remains had no meaning for the explorers.

"Do we set up here?" Ross asked. "If we could just get a report to send back...." That might mean the difference between awakening the co-operation of the Project policy makers so that a flood of supplies and personnel would begin to head their way.

"We set up here," Ashe decided.

He had selected a point between two of the lines where a reef would provide them with a secure base. And once that decision was made, the Terrans went into action.

Two days to go, to install the peep-probe and take some shots before the ship had to clear with or without their evidence. Together Ross and Ashe floated the installation out to the reef, Ui and Karara helping to tow the equipment and parts, the dolphins lending pushing noses on occasion. The aquatic mammals were as interested as the human beings they aided. And in water their help was invaluable. Had dolphins developed hands, Ross wondered fleetingly, would they have long ago wrested control of their native world—or at least of its seas—from the human kind?

All the human beings worked with practiced ease, even while masked and submerged, to set the probe in place, aiming it landward at the check point of the Finger's protruding nail of rock. After Ashe made the final adjustments, tested each and every part of the assembly, he gestured them in.

Karara's swift hand movement asked a question, and Ashe's sonic code-clicked in reply: "At twilight."

Yes, dusk was the proper time for using a peep-probe. To see without risk of being sighted in return was their safeguard. Here Ashe had no historical data to guide him. Their search for the former inhabitants might be a long drawn-out process skipping across centuries as the machine was adjusted to Terran time eras.

"When were they here?" Back on shore Karara shook out her hair, spread it over her shoulders to dry. "How many hundred years back will the probe return?"

"More likely thousands," Ross commented. "Where will you start, Gordon?"

Ashe brushed sand from the page of the notebook he had steadied against one bent knee and gazed out at the reef where they had set the probe.

"Ten thousand years—"

"Why?" Karara wanted to know. "Why that exact figure?"

"We know that galactic ships crashed on Terra then. So their commerce and empire—if it was an empire—was far-flung at that time. Perhaps they were at the zenith of their civilization; perhaps they were already on the down slope. I do not think they were near the beginning. So that date is as good a starting place as any. If we don't hit what we're after, then we can move forward until we do."

"Do you think that there ever was a native population here?"

"Might have been."

"But without any large land animals, no modern traces of any," she protested.

"Of people?" Ashe shrugged. "Good answers for both. Suppose there was a world-wide epidemic of proportions to wipe out a species. Or a war in which they used forces beyond our comprehension to alter the whole face of this planet, which did happen—the alteration, I mean. Several things could have removed intelligent life. Then such species as the burrowers could have developed or evolved from smaller, more primitive types."

"Those ape-things we found on the desert planet." Ross thought back to their first voyage on the homing derelict. "Maybe they had once been men and were degenerating. And the winged people, they could have been less than men on their way up——"

"Ape-things ... winged people?" Karara interrupted. "Tell me!"

There was something imperious in her demand, but Ross found himself describing in detail their past adventures, first on the world of sand and sealed structures where the derelict had rested for a purpose its involuntary passengers had never understood, and then of the Terrans' limited exploration of that other planet which might have been the capital world of a far-flung stellar empire. There they had made a pact with a winged people living in the huge buildings of a jungle-choked city.

"But you see"—the Polynesian girl turned to Ashe when Ross had finished—"you did find them—these ape-things and the winged people. But here there are only the dragons and the burrowers. Are they the start or the finish? I want to know—"

"Why?" Ashe asked.

"Not just because I am curious, though I am that also, but because we, too, must have a beginning and an end. Did we come up from the seas, rise to know and feel and think, just to return to such beginning at our end? If your winged people were climbing and your ape-things descending"—she shook her head—"it would be frightening to hold a cord of life, both ends in your hands. Is it good for us to see such things, Gordon?"

"Men have asked that question all their thinking lives, Karara. There have been those who have said no, who have turned aside and tried to halt the growth of knowledge here or there, attempted to make men stand still on one tread of a stairway. Only there is that in us which will not stop, ill-fitted as we may be for the climbing. Perhaps we shall be safe and untroubled here on Hawaika if I do not go out to that reef tonight. By that action I may bring real danger down on all of us. Yet I can not hold back for that. Could you?"

"No, I do not believe that I could," she agreed.

"We are here because we are of those who must know—volunteers. And being of that temperament, it is in us always to take the next step."

"Even if it leads to a fall," she added in a low tone.

Ashe gazed at her, though her own eyes were on the sea where a lace of waves marked the reef. Her words were ordinary enough, but Ross straightened to match Ashe's stare. Why had he felt that odd instant of uneasiness as if his heart had fluttered instead of beating true?

"I know of you Time Agents," Karara continued. "There were plenty of stories about you told while we were in training."

"Tall tales, I can imagine, most of them." Ashe laughed, but his amusement sounded forced to Ross.

"Perhaps. Though I do not believe that many could be any taller than the truth. And so also I have heard of that strict rule you follow, that you must do nothing which might alter the course of history. But suppose, suppose here that the course of history could be altered, that whatever catastrophe occurred might be averted? If that was done, what would happen to our settlement in the here and now?"

"I don't know. That is an experiment which we have never dared to try, which we won't try—"

"Not even if it would mean a chance of life for a whole native race?" she persisted.

"Alternate worlds then, maybe." Ross's imagination caught up that idea. "Two worlds from a change point in history," he elaborated, noting her look of puzzlement. "One stemming from one decision, another from the alternate."

"I've heard of that! But, Gordon, if you could return to the time of decision here and you had it in your power to say, 'Yes—live!' or 'No—die!' to the alien natives, what would you do?"

"I don't know. But neither do I think I shall ever be placed in that position. Why do you ask?"

She was twisting her still damp hair into a pony tail and tying it so with a cord. "Because ... because I feel.... No, I can not really put it into words, Gordon. It is that feeling one has on the eve of some important event—anticipation, fear, excitement. You'll let me go with you tonight, please! I want to see it—not the Hawaika that is, but that other world with another name, the one they saw and knew!"

An instant protest was hot in Ross's throat, but he had no time to voice it. For Ashe was already nodding.

"All right. But we may have no luck at all. Fishing in time is a chancy thing, so don't be disappointed if we don't turn you up that other world. Now, I'm going to pamper these old bones for an hour or two. Amuse yourselves, children." He lay back and closed his eyes.

The past two days had wiped half the shadows from his lean, tanned face. He had dropped two years, three, Ross thought thankfully. Let them be lucky tonight, and Ashe's cure could be nearly complete.

"What do you think happened here?" Karara had moved so that her back was now to the wash of waves, her face more in the shadow.

"How do I know? Could be any of ten different things."

"And will I please shut up and leave you alone?" she countered swiftly. "Do you wish to savor the excitement then, explore a world upon world, or am I saying it right? We have Hawaika One which is a new world for us; now there is Hawaika Two which is removed in time, not distance. And to explore that—"

"We won't be exploring it really," Ross protested.

"Why? Did your agents not spend days, weeks, even months of time in the past on Terra? What is to prevent your doing the same here?"

"Training. We have no way of learning the drill."

"What do you mean?"

"Well, it wasn't as easy as you seem to think it was back on Terra," he began scornfully. "We didn't just stroll through one of those gates and set up business, say, in Nero's Rome or Montezuma's Mexico. An Agent was physically and psychologically fitted to the era he was to explore. Then he trained, and how he trained!" Ross remembered the weary hours spent learning how to use a bronze sword, the technique of Beaker trading, the hypnotic instruction in a language which was already dead centuries before his own country existed. "You learned the language, the customs, everything you could about your time and your cover. You were letter perfect before you took even a trial run!"

"And here you would have no guides," Karara said, nodding. "Yes, I can see the difficulty. Then you will just use the peep-probe?"

"Probably. Oh, maybe later on we can scout through a gate. We have the material to set one up. But it would be a strictly limited project, allowing no chance of being caught. Maybe the big brains back home can take peep-data and work out some basis of infiltration for us from it."

"But that would take years!"

"I suppose so. Only you begin to swim in the shallows, don't you—not by jumping off a cliff!"

She laughed. "True enough! However, even a look into the past might solve part of the big mystery."

Ross grunted and stretched out to follow Ashe's example. But behind his closed eyes his brain was busy, and he did not cultivate the patience he needed. Peep-probes were all right, but Karara had a point. You wanted more than a small window into a mystery, you wanted a part in solving it.

The setting of the sun deepened rose to red, made a dripping wine-hued banner of most of the sky, so that under it they moved in a crimson sea, looked back at an island where shadows were embers instead of ashes. Three humans, two dolphins, and a machine mounted on a reef which might not even have existed in the time they sought. Ashe made his final adjustments, and then his finger pressed a button and they watched the vista-plate no larger than the palms of two hands.

Nothing, a dull gray nothing! Something must have gone wrong with their assembly work. Ross touched Ashe's shoulder. But now there were shadows gathering on the plate, thickening, to sharpen into a distinct picture.

It was still the sunset hour they watched. But somehow the colors were paler, less red and sullen than the ones about them in the here and now. And they were not seeing the isle toward which the probe had been aimed; they were looking at a rugged coastline where cliffs lifted well above the beach-strand. While on those cliffs—! Ross had not realized Karara had reached out to grasp his arm until her nails bit into his flesh. And even then he was hardly aware of the pain. Because there was a building on the cliff!

Massive walls of native rock reared in outward defenses, culminating in towers. And from the high point of one tower the pointed tail of a banner cracked in the wind. There was a headland of rock reaching out, not toward them but to the north, and rounding that....

"War canoe!" Karara exclaimed, but Ross had another identification:

"Longboat!"

In reality, the vessel was neither one nor the other, not the double canoe of the Pacific which had transported warriors on raid from one island to another, or the shield-hung warship of the Vikings. But the Terrans were right in its purpose: That rakish, sharp-prowed ship had been fashioned for swift passage of the seas, for maneuverability as a weapon.

Behind the first nosed another and a third. Their sails were dyed by the sun, but there were devices painted on them, and the lines of those designs glittered as if they had been drawn with a metallic fluid.

"The castle!" Ashe's cry pulled their attention back to land.

There was movement along those walls. Then came a flash, a splash in the water close enough to the lead ship to wet her deck with spray.

"They're fighting!" Karara shouldered against Ross for a better look.

The ships were altering course, swinging away from land, out to sea.

"Moving too fast for sails alone, and I don't see any oars." Ross was puzzled. "How do you suppose...."

The bombardment from the castle continued but did not score any hits. Already the ships were out of range, the lead vessel off the screen of the peep as well. Then there was just the castle in the sunset. Ashe straightened up.

"Rocks!" he repeated wonderingly. "They were throwing rocks!"

"But those ships, they must have had engines. They weren't just depending on sails when they retreated." Ross added his own cause for bewilderment.

Karara looked from one to the other. "There is something here you do not understand. What is wrong?"

"Catapults, yes," Ashe said with a nod. "Those would fit periods corresponding from the Roman Empire into the Middle Ages. But you're right, Ross, those ships had power of some kind to take them offshore that quickly."

"A technically advanced race coming up against a more backward one?" hazarded the younger man.

"Could be. Let's go forward some." The incoming tide was washing well up on the reef. Ashe had to don his mask as he plunged head and shoulders under water to make the necessary adjustment.

Once more he pressed the button. And Ross's gasp was echoed by one from the girl. The cliff again, but there was no castle dominating it, only a ruin, hardly more than rubble. Now, above the sites of the saucer depressions great pylons of silvery metal, warmed into fire brilliance by the sunset, raked into the sky like gaunt, skeleton fingers. There were no ships, no signs of any life. Even the vegetation which had showed on shore had vanished. There was an atmosphere of stark abandonment and death which struck the Terrans forcibly.

Those pylons, Ross studied them. Something familiar in their construction teased his memory. That refuel planet where the derelict ship had set down twice, on the voyage out and on their return. That had been a world of metal structures, and he believed he could trace a kinship between his memory of those and these pylons. Surely they had no connection with the earlier castle on the cliff.

Once more Ashe ducked to reset the probe. And in the fast-fading light they watched a third and last picture. But now they might have been looking at the island of the present, save that it bore no vegetation and there was a rawness about it, a sharpness of rock outline now vanished.

Those pylons, were they the key to the change which had come upon this world? What were they? Who had set them there? For the last Ross thought he had an answer. They were certainly the product of the galactic empire. And the castle ... the ships ... natives ... settlers? Two widely different eras, and the mystery still, lay between them. Would they ever be able to bring the key to it out of time?

They swam for the shore where Ui had a fire blazing and their supper prepared.

"How many years lying between those probes?" Ross pulled broiled fish apart with his fingers.

"That first was ten thousand years ago, the second," Ashe paused, "only two hundred years later."

"But"—Ross stared at his superior—"that means——"

"That there was a war or some drastic form of invasion, yes."

"You mean that the star people arrived and just took over this whole planet?" Karara asked. "But why? And those pylons, what were they for? How much later was that last picture?"

"Five hundred years."

"The pylons were gone, too, then," Ross commented. "But why—?" he echoed Karara's question.

Ashe had taken up his notebook, but he did not open it. "I think"—there was a sharp, grim note in his voice—"we had better find out."

"Put up a gate?"

Ashe broke all the previous rules of their service with his answer:

"Yes, a gate."