“Three kilometres from the axis—that’s slightly above lunar gravity. Dragonfly was designed for that. I’ll just have to work harder.”

“Jimmy, this is the Captain. I’ve got second thoughts on that. Judging by your pictures, the smaller spikes are just the same as the big one. Get the best coverage of them you can with the zoom lens. I don’t want you leaving the low-gravity region… unless you see something that looks very important. Then we’ll talk it over.”

“OK, Skipper,” said Jimmy, and perhaps there was just a trace of relief in his voice. “I’ll stay close to Big Horn. Here we go again.”

He felt he was dropping straight downwards into a narrow valley between a group of incredibly tall and slender mountains. Big Horn now towered a kilometre above him, and the six spikes of the Little Horns were looming up all around. The complex of buttresses and flying arches which surrounded the lower slopes was approaching rapidly; he wondered if he could make a safe landing somewhere down there in that Cyclopean architecture. He could no longer land on Big Horn itself, for the gravity on its widening slopes was now too powerful to be counteracted by the feeble force of the sticky-bomb.

As he came even closer to the South Pole, he began to feel more and more like a sparrow flying beneath the vaulted roof of some great cathedral—though no cathedral ever built had been even one hundredth the size of this place. He wondered if it was indeed a religious shrine, or something remotely analogous, but quickly dismissed the idea. Nowhere in Rama had there been any trace of artistic expression; everything was purely functional. Perhaps the Ramans felt that they already knew the ultimate secrets of the universe, and were no longer haunted by the yearnings and aspirations that drove mankind.

That was a chilling thought, quite alien to Jimmy’s usual not-very-profound philosophy; he felt an urgent need to resume contact, and reported his situation back to his distant friends.

“Say again, Dragonfly,” replied Hub Control. “We can’t understand you—your transmission is garbled.”

“I repeat—I’m near the base of Little Horn number Six, and am using the sticky-bomb to haul myself in.”

“Understand only partially. Can you hear me?”

“Yes, perfectly. Repeat, perfectly.”

“Please start counting numbers.”

“One, two, three, four…”

“Got part of that. Give us beacon for fifteen seconds, then go back to voice.”

“Here it is.”

Jimmy switched on the low-powered beacon which would locate him anywhere inside Rama, and counted off the seconds. When he went over to voice again he asked plaintively: “What’s happening? Can you hear me now?”

Presumably Hub didn’t, because the controller then asked for fifteen seconds of TV. Not until Jimmy had repeated the question twice did the message get through.

“Glad you can hear us OK, Jimmy. But there’s something very peculiar happening at your end. Listen.”

Over the radio, he heard the familiar whistle of his own beacon, played back to him. For a moment it was perfectly normal; then a weird distortion crept into it. The thousand-cycle whistle became modulated by a deep, throbbing pulse so low that it was almost beneath the threshold of hearing; it was a kind of basso-profundo flutter in which each individual vibration could be heard. And the modulation was itself modulated; it rose and fell, rose and fell with a period of about five seconds.

Never for a moment did it occur to Jimmy that there was something wrong with his radio transmitter. This was from outside; though what it was, and what it meant, was beyond his imagination.

Hub Control was not much wiser, but at least it had a theory.

“We think you must be in some kind of very intense field—probably magnetic—with a frequency of about ten cycles. It may be strong enough to be dangerous. Suggest you get out right away—it may only be local. Switch on your beacon again, and we’ll play it back to you. Then you can tell when you’re getting clear of the interference.”

Jimmy hastily jerked the sticky-bomb loose and abandoned his attempt to land. He swung Dragonfly round in a wide circle, listening as he did so to the sound that wavered in his earphones. After flying only a few metres, he could tell that its intensity was falling rapidly; as Hub Control had guessed, it was extremely localized.

He paused for a moment at the last spot where he could hear it, like a faint throbbing deep in his brain. So might a primitive savage have listened in awestruck ignorance to the low humming of a giant power transformer. And even the savage might have guessed that the sound he heard was merely the stray leakage from colossal energies, fully controlled, but biding their time…

Whatever this sound meant, Jimmy was glad to be clear of it. This was no place, among the overwhelming architecture of the South Pole, for a lone man to listen to the voice of Rama.

As Jimmy turned homewards, the northern end of Rama seemed incredibly far away. Even the three giant stairways were barely visible, as a faint Y etched on the dome that closed the world. The band of the Cylindrical Sea was a wide and menacing barrier, waiting to swallow him up if, like Icarus, his fragile wings should fail.

But he had come all this way with no problems, and though he was feeling slightly tired he now felt that he had nothing to worry about. He had not even touched his food or water, and had been too excited to rest. On the return journey, he would relax and take it easy. He was also cheered by the thought that the homeward trip could be twenty kilometres shorter than the outward one, for as long as he cleared the Sea, he could make an emergency landing anywhere in the northern continent. That would be a nuisance, because he would have a long walk—and much worse, would have to abandon Dragonfly—but it gave him a very comforting safety margin.

He was now gaining altitude, climbing back towards the central spike; Big Horn’s tapering needle still stretched for a kilometre ahead of him, and sometimes he felt it was the axis on which this whole world turned.

He had almost reached the tip of Big Horn when he became aware of a curious sensation; a feeling of foreboding, and indeed of physical as well as psychological discomfort, had come over him. He suddenly recalled—and this did nothing at all to help—a phrase he had once come across: “Someone is walking over your grave.”

At first he shrugged it off, and continued his steady pedalling. He certainly had no intention of reporting anything as tenuous as a vague malaise to Hub Control, but as it grew steadily worse he was tempted to do so. It could not possibly be psychological; if it was, his mind was much more powerful than he realized. Jimmy could, quite literally, feel his skin beginning to crawl.

Now seriously alarmed, he stopped in midair and began to consider the situation. What made it all the more peculiar was the fact that this depressed heavy feeling was not completely novel; he had known it before, but could not remember where.

He looked around him. Nothing had changed. The great spike of Big Horn was a few hundred metres above, with the other side of Rama spanning the sky beyond that. Eight kilometres below lay the complicated patchwork of the Southern continent, full of wonders that no other man would ever see. In all the utterly alien yet now familiar landscape, he could find no cause for his discomfort.

Something was tickling the back of his hand; for a moment, he thought an insect had landed there, and brushed it away without looking. He had only half-completed the swift motion when he realized what he was doing and checked himself, feeling slightly foolish. Of course, no one had ever seen an insect in Rama…

He lifted his hand, and stared at it, mildly puzzled because the tickling sensation was still there. It was then that he noticed that every individual hair was standing straight upright. All the way up his forearm it was the same—and so it was with his head, when he checked with an exploring hand.