The lantern revealed that they were standing on a narrow semi-circular platform. Another step farther and Atwood would have fallen to the tower's floor-though he would have sustained no great injury, because the years had filled the tower, like an hourgla.s.s, with so much dust and dirt that the floor was now only a foot or two down from the window. Atwood smiled and hopped down. Hard-packed, the dirt held his weight.

The lantern's light flickered yellow and black on smooth glazed walls. The tower was made of the same odd ceramic substance as the fragment Vaz had discovered in the wasteland-not stone, precisely, nor brick. Overhead, a series of perches and struts and narrow beams spiralled up into the darkness. No cobwebs; no bats or owls or scurrying mice. Silence, and a smell of metal.

"Ancient," Arthur said. "It feels older than the hills, somehow."

Sun lowered himself gently to the floor, and looked up. "Isn't that always the way with ruins, Mr Shaw? The things of Man are measured in years; the things of G.o.d in millennia."

"True enough."

Arthur leaned out the window.

Outside, Payne and Frank held rifles at the ready. Vaz held an ice-axe in his hand. Dimmick seemed to have wandered off around the back of the tower.

"It's empty," Arthur called. "It's safe. For G.o.d's sake, stop waving those things about before somebody gets hurt."

"Empty?" Sun continued to stare upwards, hands folded behind his back. "Perhaps."

"Shaw," Atwood called. "Bring that lantern here."

Atwood knelt in the dirt, inspecting the wall on the far side of the tower.

"There, Shaw. Hold it up."

The lantern revealed scratches on the wall. A spider's-web tracery of shallow lines and curves.

"Markings," Atwood said.

"Hieroglyphics?"

"Perhaps-if you like."

"They look like scratches, to my eye-the wind and the rocks could have made them."

"Do they? Well. Look, though." Atwood scrabbled in the dirt. "Whatever they are, the greater part of them is buried-what a nuisance! Hidden by the years; swallowed by the sands of Mars themselves..."

"Well. We have shovels, don't we?"

"What a literal mind you have! Yes. I suppose we do. Then let's have Dimmick and Frank dig. Vaz and Payne should remain outside with the sleds. We may be here some time. Don't you agree, Sun?"

"I think I will defer to Your Lordship."

Atwood stood, rubbing his hands together. His palms were red-he'd cut them digging in the dirt. He put a hand on Arthur's shoulder. "Who knows what these markings may teach us, about Mars, about the heavens."

"Will they teach us how to find Josephine, or how to get home?"

"Be patient, Shaw. I said that we would find evidence of Martian civilization. And look: we have."

"Yes," said Sun, still staring up into the rafters.

Red dust drifted down and into their little circle of light.

Frank and Dimmick didn't share Atwood's enthusiasm for the tower; in fact, they found it positively eerie, and they kept their rifles close at hand as they dug.

After a while, Arthur stopped Frank and took a turn with the shovel. Digging was something to do. Preferable to just standing around. Whatever Atwood saw in the scratches they were uncovering, it was all meaningless to Arthur. Certainly it resembled no language he was familiar with. How could it?

They piled up dirt under the window, and periodically heaved it out and over the side, creating a growing heap next to the sleds. Through some peculiarity of the arid Martian atmosphere, it was possible to work vigorously for hours without ever sweating. It was a strange sensation.

Frank took over again. Dimmick was indefatigable. Sun lowered himself down the rope from the window, and paced around the perimeter of the tower as if marking the boundaries-Arthur presumed there was some mystical purpose to this. Meanwhile, Atwood sat cross-legged on the stone platform, the lantern beside him, making sketches of the tower and its markings.

Every so often, someone's shovel slipped and made a fresh scratch on the wall. The first time that happened, Atwood flew into such a rage that it seemed he might have someone hanged. After a while, he became resigned to it, and merely sighed. Arthur began to wonder if perhaps all the markings had been made that way. Centuries of explorers, digging and scratching, the hourgla.s.s refilling after they were gone. Elizabethan mystics, medieval monks travelling to Mars in their visions, Romans and Greeks, Buddhists and Hindus and Aztecs too. Or Moon-men or Venusians, for that matter.

The setting sun found its way in through the windows and filled the tower with sharp angular shadows. Outside, it cast weird shadows across the dunes, which seemed almost to creep and ripple of their own accord. Or so Vaz reported, when Arthur and Frank and Dimmick came down from the tower, having decided, after long discussion, that they would rather sleep outside than in. When Arthur finally fell asleep, the lantern still glowed faintly from the window above. Atwood remained at work. Sun was still pacing the boundaries.

When Arthur woke, his bladder ached. First time since he'd set foot on Mars. The body's ordinary functions were slower here; or they were a mere illusion, a matter of habit. He ignored the urge, and it went away.

Eventually, reluctantly, he sat up. He ached all over. The aches didn't go away no matter how long he waited. He appeared to be developing an unpleasant rash on the back of his hands. Too much scrabbling in the dust and the dirt, perhaps.

Sunrise behind the tower. Cold and blue. He watched it for a while.

Vaz and Payne and Frank were still asleep. Atwood was presumably up in his tower. Since there were sounds of digging, Arthur supposed that Dimmick was in there too. Mr Sun sat on top of a nearby dune, watching the sunrise. Arthur went to join him.

"Shaw," Sun said, without turning around.

"Just think," Arthur said. "Somewhere that same light is shining on London."

"It isn't," Sun said.

"No?"

"It is not the same sun it once was. Nor are we the same men."

Arthur looked down at Sun. The back of the man's neck looked burned, as if he were starting to develop the same rash as Arthur.

"In a mystical sense, I suppose you mean. No man can step in the same river twice-that sort of thing? Well, fair enough. But I'm literal-minded, Sun. It's my refuge against madness."

"Then by all means believe what you will, Mr Shaw. I would not want to destroy your refuge against madness. Not now."

"Sporting of you."

The sun pa.s.sed behind a dust-cloud. A shadow fell across the dunes. The whispering picked up slightly, as it often did in shadow.

"Atwood plans to keep us here for some time, I think."

Sun nodded.

"Studying the language. Does it make sense to you, Mr Sun? What he's finding-is it language?"

"Perhaps. I don't know. I have come to think that Lord Atwood knows more about this place than I had expected. Don't you think?"

"From the way he talks, you'd think we were all just things in his dream."

"Is it not a fine dream, though? Is it not beautiful?" Sun gestured out at the horizon. The sun now pierced through the black clouds with rays like needles of blue ice. He closed his eyes, and said no more.

"The men don't like this tower," Arthur said. "I don't either. When I said it was empty, you said perhaps-what did you mean?"

"I meant nothing, Mr Shaw. I know no more than you do. Do you think I travel to Mars often? Who knows what we may see tomorrow? Ask Lord Atwood. I meant what I said. Perhaps. Let me ask you a question. If Josephine is alive, she has been here for a long time, beneath this sun, this sky. Not dead, but changed; what do you imagine she has become?"

Arthur kicked at a rock, sending it skidding across the dust toward the tower. d.a.m.n the man! He didn't like Sun's insinuations; not about Josephine, nor for that matter about Atwood. If there was to be some rivalry between the two men, Arthur wanted no part of it. He had a job to do.

"You're right, Mr Sun."

"Am I?"

"Quite right. Just as you say. There might be anything in that tower. I should explore it for myself. Thank you, Mr Sun."

"Good luck, Mr Shaw."

He went back to the foot of the tower, where Payne and Frank and Vaz were waking, and proposed an expedition into the upper reaches of the tower.

"Go to h.e.l.l," Frank said, speaking for himself and Payne. "We're not budging from these sleds, not for you or anyone else."

"I don't like the thought of climbing the tower," Vaz said. "But nor do I like the thought of spending all day with nothing to do but listen to the wind and these gloomy fellows moaning. I'll come with you. Besides, I am a first-rate climber, and good with ropes; that's why his Lordship brought me here."

The tower's builders hadn't needed stairs. There were nothing but the beams and ledges overhead, spiralling up into the dark and growing more remote every hour, as Dimmick's shovel steadily lowered the floor.

They had no ladder, but they had rope. They tied a kettle to the end of a rope, and after several failed efforts, one of which nearly concussed Dimmick, managed to lob the kettle over the lowest of the beams. Vaz, as the lighter and more athletic of the two, went up first, with Arthur and Dimmick supporting the rope's other end. Then Vaz secured the rope around the beam and Arthur followed him up. Balancing carefully, Vaz flung the rope again, over the next-lowest beam, and so on. They moved in this manner up through the tower's spiralling interior, pulling the rope up behind them as they went. It would have been quite impossible on Earth, but under the feeble Martian gravity, they made decent time. Within a quarter of an hour, the floor below was gone from sight. Atwood's lantern was a faint yellow glow. Soon even the sound of Dimmick's shovel faded.

There were windows every six feet or so, arranged haphazardly around the tower's circ.u.mference; a perch outside, and a narrow ledge inside. A view from the windows across endless plains. No furniture, or none that had survived. No decoration. No further markings. Perhaps the Martians roosted there to sleep, once upon a time. Dust heaped in the corners.

The top of the tower came closer. Faint daylight crept through the rafters overhead. They clambered up onto another ledge. There was another window, and another heap of dust-which, on closer inspection, appeared to contain bones.

They approached the bone-heap with trepidation, shoulder to shoulder, practically hand in hand.

"After you," Vaz said.

Arthur gave the heap a poke with his foot. A tangle of bones, held together by sc.r.a.ps of some ancient fabric-or, G.o.d forbid, skin-slid from the dust. The bones were plainly inhuman: long and tapering, light, paper-yellow. Whatever they were, there was no visible clue to the manner or cause of death. Vaz crossed himself.

They flung the kettle up over the next beam and pulled themselves up again.

After three more turns of the spiral-past three more windows, and more heaps of dust and bone, which they did not inspect too closely-Arthur stopped, overcome by a nagging sensation that there was something he'd overlooked. He put a hand on Vaz's shoulder and stopped him from throwing the kettle again.

"The windows," he said.

"The windows?"

"Yes-yes, Vaz. Or, rather, the view. Come, here, look."

At some point in their climb, the shape of the windows had changed. Lower down, the windows were tall narrow slits, but farther up they were round, and hardly more than a foot in diameter-too small for anyone to enter; even, one would imagine, a Martian. The view through them had changed, too, some three or four revolutions ago, but Arthur hadn't fully noticed the change until now. He had to examine it closely to be sure he wasn't imagining it.

Though the window was empty, looking through it was somewhat like looking through a finely crafted lens. It commanded a view across vast plains and into the mountains; and yet it seemed somehow focused on one particular point in the distance, in the foothills of a mountain range, such that when one looked at that region-and only at that region-one could see it as if it were only a few yards away. The effect was tremendously disorientating. There was nothing to see in that distant region, nothing but rocks and hills and dust and shadow; and yet the fact that one could see it at all was extraordinary.

They lowered themselves back to the previous ledge. That window, naturally, faced in a different direction, and the point on which it was focused was different. It was almost equally nondescript, although this time, in addition to rocks and dunes, the zone of magnification contained a squat and empty-looking stone ruin.

"Lord Atwood will want to know about these," Vaz said. "Perhaps we can use them to plan our course."

"How do you suppose they work? Some sort of-some sort of ray, perhaps? Or something in the air, a gas or a ... Yes. Atwood should know. Are there more? How do you suppose one controls them?"

They kept climbing. They pa.s.sed by more bone-heaps without further curiosity. Next they found a window focused on a distant mountain, and then one that was focused on a region of cloudy sky. Perhaps, Vaz guessed, if they waited until nightfall it would illuminate a distant star, or one of the moons.

By the next window they had revolved half-way around the tower, and now they looked out west. The tower stood in a sort of shallow depression, they observed; the ground sloped up slowly into a great plain, under low-hanging clouds. In the far distance was an impossibly tall and tapering mountain. The window's zone of magnification lay at the mountain's foot. A storm was brewing there, great whirling winds rushing down off the mountain into valleys of dust and sweeping up enormous black clouds. Thrilling to watch, but terrifying; Arthur was very glad for the countless miles that lay between him and the storm.

After a while, Vaz scratched his head and asked if it was just his imagination, or wasn't the storm, miles wide, moving in their direction, and rather rapidly?

"Good Lord," Arthur said. "Good Lord. I believe you're right."

"I've seen enough, Mr Shaw. Let us return to Lord Atwood and make our report."

They went for the rope-both hurrying, unable to resist the sensation that the dreadful storm was somehow right at their backs. Arthur stumbled across a heap of bones and dust. There was a sudden agony in his leg, as if a snake had bitten his ankle, or as if he'd received an electric shock. There was a smell of burning in his nostrils, as if his moustache was on fire. Vaz cried out in pain. Arthur felt something clawing at him-clawing in his head, as if fingernails were sc.r.a.ping the inside of his skull. Vaz fell forward and toppled off the ledge into the darkness. Arthur recalled the training in magic that Therese Didot had given him-how he'd grumbled at the time!-and summoned into his mind a sigil of warding, of peace, of calm. The thing in his head shrieked wordlessly and battered at his defences. He fell to his knees. Before him, a tall shape-two tall shapes-rose up out of the heap of bones and dust. He looked up at long legs, narrow shoulders, long axe-thin faces, expressions of madness. They opened pale and ragged wings. They were creatures of the same species as the thing in Atwood's library-Martians. Not dead, these two, not like the others-not mere bones. They'd looked like bones because they were so terribly, excruciatingly thin. Not dead, but sleeping-for how long?-on a dead world. One of them reached for Arthur. He lunged forward between their legs and seized the kettle, which he swung up into the nearest face. That one crumpled. The other one spun, slashing its wing's ragged edge towards Arthur, and he stumbled back and slipped off the edge of the ledge. He landed on one of the beams, and slid off-bouncing off the next beam down, and falling again. He landed on a ledge, rolled off, and finally came to rest, panting and in agony, G.o.d knows how much farther down.

"Vaz!" he called. From somewhere in the darkness above, Vaz answered him. He couldn't see Vaz, but he could make out motion overhead, glimpses of those horrid pale wings, as the half-skeletal creatures were hopping down from ledge to ledge. From below, he heard Atwood calling up, demanding to know what was happening. Since there was clearly no way he could get up to Vaz at present, and since he didn't fancy wrestling with those monsters alone, Arthur began lowering himself-carefully, but not carefully enough; he slipped again, bounced again, and before he knew it, he was lying on his back on the sand, looking up at Dimmick's grinning face. In the next instant, Dimmick heard the buzz and click of the creatures' wings and the grin disappeared from his face, along with whatever joke he'd been about to make at Arthur's expense. He grabbed for his rifle as the creatures descended out of the rafters; shot one and it fell. The other kicked out at his head and knocked him sprawling. Arthur tried to get to his feet but seemed to have momentarily lost the use of his legs.

"Stay!" Atwood shouted. He seemed to be speaking more to the monster than to Arthur.

The monster stopped. It hung in the air, watching. Arthur craned his neck. He couldn't quite see Atwood, who stood behind him-he could see only Atwood's shadow on the wall, cast by the lantern behind him, as Atwood performed-Good Lord, what was he doing? It began with subtle and occult pa.s.ses and worked up into jerking inhuman motions of hand and arm-he appeared liable to dislocate his shoulder or break his neck. The creature hovered-an extraordinary motion, not buzzing or beating its wings, but rippling them-and then it turned and fled for the nearest window, nearly knocking Sun over as he climbed into the tower.

Atwood stretched out a hand and helped Arthur to his feet. Sun looked out the window for a moment, then apparently decided that the creature was gone.

"Very well done, Lord Atwood," Sun said. "You must teach me that trick."

Arthur sat against the wall and caught his breath. No bones appeared to be broken, for which he supposed he had the feeble gravity of Mars to thank. He watched Sun and Atwood and Dimmick go up into the rafters, and he watched Vaz-whose condition was much the same as his-come clambering down.

When Atwood came back down, he was in a near-faint from exertion. Sun helped him to sit against the wall, and called for cocaine.

"Well?" Arthur said.

"A storm is coming," Sun said. "Perhaps they are common here. In any case, we cannot evade it on foot. And so we will remain here in this tower until it has pa.s.sed. In the meantime, we will continue our study. Dimmick, please fetch Payne and Frank and bring in what we can of the supplies. And bury the rest."

Atwood waved. "Go. Good shooting."