My men were in battle dress for the landing—steel helmets painted green, dirty green jackets, pants, cartridge belts, heavy field shoes. The Caribbean was so deep blue it hurt the eyes. You could look straight down into it until it made you dizzy. Sharks, some of them monsters, congregated from all directions.

Marines waiting to debark shouted derisively at the sharks; but it was noticeable that they didn't pull any funny business on the slings, and they didn't let go of the slings until their feet were firmly planted in the bottom of the landing craft. The landing craft scarcely rose and fell. The Caribbean was as smooth as an inland lake. I think, now that I look back, that all of us had a strange feeling that something unusual was going to happen, and that it had nothing to do with the sharks.

I was first aboard a landing craft. I moved to the outboard side of my craft and looked toward the half-moon beach where the Yataritas empties into the Caribbean. The river's mouth was hidden by the sandy beach. To my right the coast of Cuba, rugged, dirty coral cliffs ten to fifty feet high, led away eastward, bulging out gradually a mile south of the white-sandy beach. To my left there were broken cliffs of rotting coral, and slopes leading up gradually from the shore to cactus and spined-brush-covered hills so round they cast no shadows.

Captain Ross Haggerty crawled down into the second LCVP, First Lieutenant Peter Hoose into the third. There were twenty-four men with each of us, some veterans of two wars, some recruits who'd been too young for World War II.

We were going in with Haggerty to my right rear, Hoose to my left rear. We were equipped with the latest in ship-shore-landing-craft-airplane communications. Four jet planes did fancy stuff over us, over the beach, and behind the beach, while we got into our places. I could talk with anybody in any LCVP, aboard the Odyssey or in any one of the jets. Our headsets made us look like men from Mars.

Every man who was participating in this maneuver wore one of the sets, for experience had taught that any marine, at any time, might find himself running the show.

There were flecks of foam about the reefs which flanked the half-moon beach when all three LCVP's rose on their steps like amphibians ready to take off, and headed north for the beach, so white it dazzled the eyes. Behind the beach lay the spined brush wherein, theoretically, enemy troops were lying in wait to rip us apart.

I always thrilled to a landing, even a make-believe one. So did the men, boring though peacetime soldiering was. The APD was dropping dud shells ashore. The jets were diving on us, just to make a noise, and our three motors sounded like the crack of doom. The men kept down because that was the rule, but occasionally I pulled myself up and looked ahead over the ramp—which would come crashing down when we rammed our nose into the sand. Out over that ramp the marines would charge, to race for cover and swing into position to give our new weapons a workout.

We'd be in in five minutes. The boat-handlers were talking to the ship and the jets. I just listened in. I didn't see or hear a thing out of the ordinary.

"Stand by!" came the cry. "We're smacking in a coupla seconds!"

The jets were having fun right over the beach and for a moment I envied their pilots. When we got ashore it was going to be like sitting atop a burning galley stove, on that sand. It would be even worse under the brush on the land beyond that rose to the hills and the coral cliffs which crowned them.

The other two LCVP's had drawn abreast now. We hit the beach nearly together. I heard the rasping of the chains as the ramps went down, hitting the sand. There was knee-deep water over the outer ends of the ramps. The marines dashed ashore. The first odd thing happened then; one instant there was water over the ends of the ramps, then there was none.

As a matter of habit every marine did his job. Without command, they sprayed out to right and left, getting unbunched as quickly as possible, just in case a theoretical enemy projectile should land among them.

But their deployment slowed and came to a halt. I think they, like myself, must instantly have missed the racketing of the jets. I looked up. The sky, a pale blue, with slowly moving clouds in which I was aware of greenish tints, was utterly empty of the four jets which were supposed to support our maneuver.

I whirled and looked back. Where the Caribbean had been there was a huge sprawl of desert, blinding in the midday sun, stretching away southward to a semicircle of brooding hills. I judged their crests to be at least four thousand feet high. And where those crests were, five minutes before, the Caribbean had been—fully a mile deep under the stern of the Odyssey! Where the Odyssey might now be I hadn't the slightest idea.

Just before we hit the beach there had been thickets of broad-leaved squatty trees behind the ridges of sand, into which the marines had been headed for concealment. Now there was nothing of the kind. There was nothing but sand and silence—silence so deep that even breathing broke it into brittle bits.

The three LCVP's were still with us, high and dry on the sand in the middle of the desert. Each was manned by a coxswain and a radioman. These six men—they were sailors, of course—were now sitting in their positions aboard the three crafts, like statues; as if they had been fossilized by the suddenness of whatever had happened.

At first I thought something was wrong with me. Then the marines became uncertain, and when marines are uncertain the situation is definitely out of hand. If I was seeing things that weren't there, so were seventy-four other marines and six sailors.

Captain Haggerty was giving the "assemble" signal and pointing to me. Even before he gave it the marines were walking slowly toward me, their weapons at ready, their eyes taking in all there was to see. I moved back to the central landing craft.

"My radio is dead," I called. "How about yours?"

"Nothing, sir. They couldn't be deader on Judgment Day!"

I leaned against a corner of the LCVP and waited for the men to assemble. Nobody said anything. They just looked at me. I felt helpless.

"First," I said, "let's make a check. I want to be sure I haven't gone completely daft! If what I say is true, say 'Aye, aye!' Got it?"

"Aye, aye, sir!"

"This is not the Yataritas Beach we all know—apparently!"

"Aye, aye, sir!" the voices were low, hesitant, yet sure.

"The Caribbean has disappeared!"

"Aye, aye, sir!"

"No jets! No APD! No anything we know—except sand!"

"Aye, aye, sir!"

"And we have no communication with anything, anywhere. I've no idea what we ran into, but it happened just as we hit the beach." I looked at my watch. "And one more thing. We landed about ten minutes ago, at nine hundred. The sun says it's nearly thirteen hundred. My watch says it's oh-nine-twelve exactly."

Officers and men looked at their wrist-watches.

"Aye, aye, sir!" They all agreed to that.

"The sailors are inside the—area—whatever it is, or they would be gone like everything else except the LCVP's. Somewhere behind the LCVP's, then, should be—"

But I couldn't say it. Everybody could see that behind the LCVP's was the unknown desert leading away south to the brooding ancient mountains.

Sergeant Eckstrom strode quickly to the rear of the LCVP's. That took guts, for he might have disappeared; but he didn't. He walked out onto the hot desert for twenty yards, turned and came back. That ended that. We were seeing what actually was there.

"We'll send out scouts," I said, "to the four cardinal points of the compass. We'll split each quadrant with another scout. That's eight scouts. Make it sixteen, scout in pairs. Don't get out of sight of the landing craft. No telling what you may run into."

We officers split the horizon into thirds, set out to reconnoiter.

The sailors flatly refused to leave the LCVP's further than the almost non-existent shade they cast. It was their way of grasping at something they could understand. I didn't blame them or argue with them. The skipper of the APD was their immediate superior. Where was he, anyway?

What had snatched us into this unbelievable Limbo?

How had it been done? What was going to happen to us?

I traveled about four points north of the northeast group. I am a fast walker; even through sand I can travel faster than most men. I was slightly ahead of all the other groups when suddenly I could go no further. I could feel nothing, yet when I put out my foot to set it down in a new place, it struck an invisible something, dropped back, and my impetus carried me forward to involve my face in something much finer than cobwebs.

I jumped back, swearing, for I could see nothing except the hot waste of glistening sand. There were dunes, hummocks with strange grasses and brush sticking up through them like beards; but I had struck the limit of my trek and could not reach any of those visible spots beyond.

I pushed against it with my hands. It gave, but only as a taut wire net might give, then press back against the hands; it was a strain to make the thing bulge. The counterpressure was strong. I could not advance. I turned to the right and saw that the nearest patrol had stopped. The two men were fumbling in the air like blind men. They were raising and lowering their feet as if they felt for steps above an abyss. They, too, had come to the end of possible advance. They had come into contact with invisibility also—invisibility that was inflexibly tough beyond a certain brief limit.

The two men turned now and looked at me. I gave the halt signal and started toward them. I ran into something and caromed off, falling to my knees. The horrible thought struck me that each group might have stumbled inside some hideous globe and become separated from all other groups. But it wasn't so. I got to my feet, put my left hand out against the invisible wall—which felt warm to the touch, as if it were a living thing—and started toward the northeast group.

The surface of that strange substance was undulant; it zig-zagged, like the weaving walk of a drunken man.

I reached the first patrol, Corporal Hoge Ziegler and Private First Class Barry Preble. Their faces were white. I wouldn't say they were scared but they were definitely concerned.

"Well, at least we've discovered what it was we ran through at the moment we hit the beach," I offered. "All we need to do is find a way through it, and go on with our maneuver."

Ziegler shook his head. "No, sir, I don't see it like that. We can see through this stuff, or seem to, but we can't see back the way we came, astern of the landing craft."

"Right, corporal; what do you think it is, then?"

"I'm no scientist, sir. I'd say it is a net of some kind, in which we have been caught, landing craft and all, like so many fish. But by whom? By what? For what reason? It has me stopped."

"I wonder—" began Preble, then stopped, staring at the place where he and Ziegler had come to a dead stop. Preble stepped back. In his arms he cradled one of the latest automatic weapons.

Preble stepped back, lifted the muzzle of the weapon, held down the trigger for a few squirts. The weapon acted naturally enough. There was no question that the bullets left the muzzle of the fast-firer. But we didn't hear them hit the invisible screen; nor, looking beyond it, did we see where the bullets kicked up sand. The bullets simply plunked into nothingness as bullets of an obsolete day vanished into soap or sand during firing tests.

A few seconds passed. Then there were soft sounds in the sand at the very spot where the two marines had hit the wall. All three of us looked down. The flattened, steel-jacketed bullets lay in a small group in the sand, within a couple of inches of the invisible wall—on our side of it.

"Caught the bullets, like a baseball catcher!" said Preble, his voice high-pitched with threatened hysteria. "Then just dropped 'em! Took them in, killed their speed, then slowly discarded them! And I saw the wall do it!"

Ziegler and I had not seen this phenomenon, but we were not directly behind the weapon, as Preble was.

I lifted my binoculars for the first time and looked around at the other patrols, all of which I could see easily. All except those which followed a southerly direction had come to the wall and were just as puzzled by it as we. None of us had anything to offer; we were even afraid to think lest we question our own sanity.

We held our ground until all patrols had come up against the invisible wall. Then we had some idea of the extent of our prison. That brooding mountain to the south, it appeared, was forbidden to us.

How high did the wall reach? Was it domed?

"Preble, fire as nearly straight up as you can," I told the private. "Then we'll duck away fifty or sixty yards, just in case, and listen."

Ziegler and I stepped well back. Preble took careful aim. He squirted a few score slugs, then ran to join us. We were so silent we could not even hear each other's breathing. Shortly we heard the bullets drop into the sand, and stepped forward.

Theoretically a bullet fired straight up strikes the ground with the same speed at which it was fired—so the slugs would have been flattened anyway. But we had noticed a thin film of some substance unknown to us around the slugs which had been first fired into the wall.

That same substance was clinging to the several slugs we managed to sift up from the sand. Our wall of invisible tension was a dome!

"I feel like a bug!" said Preble. "I feel like a bug must feel when a scientist wants to study it. The scientist keeps covering it with a glass tumbler when it tries to walk or fly away!"

"Do you suppose our own authorities," said Ziegler, "would be trying out a new interdiction weapon on us? Major, they wouldn't do it without at least telling you, sir, would they?"

"They might," I said. "There are secret weapons only the highest high brass knows about. But if your hunch is right, corporal, we've sure got ourselves something, haven't we? Wouldn't it be something if we could throw an invisible net over every dive bomber of an enemy, every warship, every man, and nullify the attack before it got started?"

"It would make them all feel pretty silly," said Preble. "But suppose an enemy had such a 'net'? Suppose it could reach out from anywhere in the world—"

Slowly we all walked back to the LCVP's.

"Something else funny," said Ziegler. "It's noon now, by our time. The sun says it's about four in the afternoon or thereabouts. But we're still ordinary marines, aren't we? Maybe I'm different from the rest of you, but doesn't it strike you as off—"

"I'm not hungry," said Preble. "Nor thirsty! By this time of the day, when we had breakfast at oh-six-hundred at Guantanamo, I'd be starving." Preble was the company chow-hound. "But I'm not hungry, or thirsty. You, corporal?"

Ziegler shook his head. He was by way of being a hearty eater himself, while I confess I came as close to being a glutton as an officer and a gentleman dares allow himself to be.

We had hiked for several hours under a blazing sun. Moreover, all of us had sweated away a lot of moisture. Each of us carried a canteen of water, so water was not yet a problem; but the point is, none of us had taken a drink!

When we got back to the LCVP's it was to find that nobody else was either hungry or thirsty....

"We're prisoners," said Captain Haggerty, "that's clear. And according to the laws of war, prisoners are fed. If we've been fed, and given water without eating or drinking, how?"

"Through our pores!" said Preble impetuously.

There was a long moment of silence which somebody had to break pretty soon.

Lieutenant Hoose broke it.

"Personally, I don't want to be sprinkled by something invisible, even if I'm dying of thirst. And if food is being somehow rubbed into us, I'd just as soon nobody rubbed it in! I'm not too lazy to chew for myself!"

It brought the first laugh. Hoose had a drawling manner of speech which sometimes caused the men in ranks some discomfort to keep their faces straight. We were more relaxed than we had been, for we appeared to be in no danger. Besides, we were extremely well armed. If anybody attacked us—but I refused to think too much about that. I had a sneaking hunch that our top-secret weapons were, in this place, just so much metal, value zero.

Now and again, during a comfortable afternoon, I sent out patrols to check on the invisible wall. They always found it. Either it was there continuously, or it was dropped when nobody was near and hurriedly restored when a patrol went out to check.

The feeling that everything we did or said was noted and heard began to make us wary of movement and speech. We tried to pick out vantage points from which we could be seen. Any one of the dunes outside our prison might have hidden something. But discussing it, none of us felt that this was up to the standard of behavior of whatever it was that held us.

That's about as far as we got before the sun went down with startling suddenness and darkness settled over our Limbo. The darkness was impenetrable. It lasted perhaps an hour. Then a sort of haze seemed to withdraw in all directions, inwardly and outwardly—and the wondrous tropical sky, studded with stars that hung down almost within reach of human hands, bathed our upturned faces.

In silence we all watched. There was an unusual coolness in the air, too, for several minutes, Cuba, at that time of the year, was almost never cool, even late at night; but some of the men were shivering. Sweat had not dried on all of us, and sweat is bad when you are motionless, at night. I was about to order the men to exercise a little, when I realized something that Hoose put into words first:

"Now," he said, "they're feeding us warmth, just as they feed and water us! And we've been here for hours and don't have any idea, even, who or what they are!"

Nobody else said anything. All the rest of us were studying the sky.

"I don't see the Big Dipper!" said Sergeant Eckstrom.

"Nor the North Star!" somebody added.

"Nor Venus, nor Lyra!" said someone else. "I've been studying our books on constellations, and I don't recognize a one! Where are we? We're not even in Cuba! Not even in the Northern Hemisphere! Not even—"

"Not even on the Earth—?" said Hoose.

It was just here that the whispering began in our walkie-talkies; whispering like nothing we had ever heard. We could make out nothing that sounded at all like human words. The sounds were mechanical, yet not-mechanical. I've called them whispers only because that comes closest to describing the eerie sounds which every last one of us was now hearing in his walkie-talkie.

"It's vibration on our wavelength," said one of the gobs. "But that's the best I can say of it."

"Morse? International?" I asked.

But nobody could offer an answer.

Right after that we saw the Shadow Men, inside the dome. Something of that which held us at last became visible.