It was a ring, measuring three centimetres across. Made of titanium.

‘Commonwealth artefact,’ Nigel said.

‘Not jewellery,’ Fergus said. ‘It was fixed into the fabric.’

‘Any more of them?’

‘I can’t see any, no.’

‘All right, let’s keep going.’

They began moving forwards. Ten minutes later Nigel called a halt. He dismounted and picked up another scrap of cloth. Like the first, it disintegrated as soon as he touched it.

‘Ancient,’ was all he’d say. ‘Very ancient.’

There were more tatters of the frail cloth scattered over the desert. Snagged on stones, half buried under tiny rills in the sand. One they saw had a cable attached, which was twisted round a flinty rock.

Nigel and Fergus knelt beside it, examining the find. ‘Monobonded carbon filament,’ Nigel said. Fergus gingerly started pulling it. More fabric puffed into dust. The filament was ten metres long, one end connected to a metal clip of some kind.

‘So did a ship crash here or not?’ Kysandra asked.

Nigel kept his shell perfectly opaque. ‘Maybe. These fragments are certainly left over from that era. The wind must have blown them about from whatever’s out there. I just don’t quite get what the fabric was. Maybe some kind of tent?’

For another two hours they kept going. More and more torn ribbons of the ubiquitous cloth were scattered about. They saw one patch that was over three metres across, draped tightly over several stones and rills, age and sun conspiring to tighten it into a skin that revealed every crack and blemish it covered. Under the eerie nebula light, it shone a pasty blue-grey against the dark sand, as if it was a lost smear of bioluminescent lichen.

‘How long can fabric survive out here?’ Kysandra asked.

‘This stuff is a polymer residue; there’s no telling what it decayed from, so I don’t know the timescale,’ Nigel said. ‘But there’s a hell of a lot of it.’

‘Got something,’ Fergus called out. ‘Switch to infra-red and look at the horizon.’

Kysandra switched to infra-red. It was a mode she’d avoided: turning the desert ground to a speckle pattern of pink and yellow in the middle of the night was disorientating, especially with the blank sky above. But there it was before her now – an exquisite level plain of glowing colour, fluctuating in slow undulations as residual heat leaked back out into the mild air. She frowned. Out there at the very limit of the gentle tangerine illumination, where heat gave way to emptiness, a green blob straddled the rim of the desert. She tried to zoom in, but the higher the magnification, the more blurred the thing became.

‘What is that?’ she asked cautiously.

‘Something a different temperature to the desert,’ Nigel said. ‘Something big.’

‘The monster?’ Madeline asked fearfully.

‘There is no monster,’ Nigel said.

‘Let’s go,’ Fergus said. ‘We might reach it before dawn.’

They tried hard, urging the horses forward in a fast walk. But after another forty minutes, the green glow didn’t appear any larger and dawn spread a brilliant sheen of monochrome light across the desert. As shadows thrown from them and the horses stretched out across the ochre sand, they stared at the horizon directly ahead. A small conical hill rose out of the barren terrain, its shallow slopes a curious slate grey, turning to a lighter ash shading as the sunlight slithered down it.

‘That’s not a ship,’ Kysandra blurted.

‘Doesn’t look like one,’ Nigel agreed. ‘But it’s definitely metallic. That has to be the spectrum Skylady’s sensors detected. This is what we’re here for.’

Even as he was talking, Kysandra was studying the ground around them. The shreds of fabric were everywhere. Hundreds – thousands – of tattered streamers lying without order, from the size of a handkerchief up to sheets that would have covered the bed back in the Rasheeda Hotel; lacing the sand between them was a multitude of thin filaments, some stretched out flat, others tangled in knots. There were also little chunks of tarnished metal – clips and bolts which the filaments were attached to. The ubiquitous rings.

‘How far to the metal hill?’ Kysandra asked.

‘Difficult to measure,’ Fergus said.

Even as she zoomed in again, Kysandra could see the desert stirring. The air swelling and flowing as the sun began its tremendous bombardment.

‘Let’s press on,’ Nigel said. ‘We might get there before we have to make camp.’

Kysandra thought that unlikely, but said nothing. The little convoy rolled along, with puffs of dust swirling up whenever a hoof or a wheel ran over a patch of cloth, causing it to disintegrate instantly. At the beginning, they were dismounting every couple of minutes to remove filaments that had tangled round the legs of the horses. After that, whoever took point used teekay to clear the strands away.

Now, the track they left behind was like a path of destruction, a trail anyone could follow. When Kysandra scanned round, she couldn’t see any other furrow through the delicate scraps of cloth.

‘Nobody else has been here,’ she decided.

‘Not for a long time,’ Nigel agreed.

The hill was definitely larger when they stopped two hours later. Her zoom function still wasn’t much use through the wavering heat, although she was convinced the sides of the hill were exceptionally knobbly. She was also intrigued by the uniformity of colour. The cone shape was nearly perfectly symmetrical, too, though it was odd, with a wide base, as if it had sagged at some time since its formation.

‘Why would you cover a hill in metal?’ she asked as they put the tents up.

‘There is no reason for that,’ Nigel said. ‘But then, I don’t think it is a hill, either.’

‘What then?’

‘Some kind of ship. Nothing else it can be.’

‘Is that what the colony ships looked like?’

‘No. At least, not any human one I know of.’

That made her shudder.

Despite a hard night in the saddle, Kysandra could only doze through the long day. She was bursting for them all to get back on the horses and ride to the hill. Solve the mystery! Though some deeper, more cautious, part of her mind was urging her to turn round and gallop for Croixtown, sail cleanly down the river and be safe.

‘Do you want to go home?’

Kysandra snapped fully awake, staring belligerently at Nigel, who was lying on his mattress next to her. She tightened her shell immediately, annoyed that she’d been spilling her drowsy thoughts. Irritated with him, too, for studying them. ‘No!’ she snapped. ‘This is a mystery that even you don’t understand. I want to find the answer. I want to know what’s out there.’

Nigel grinned. ‘That’s my girl.’

They watered the horses and packed up the tents. This time the pace was less frantic than it had been that morning. They’d been travelling for ninety minutes, with the sun dropping close to the mountain peaks, when they found the first body. It was sprawled on a crude cart, made from what looked like a circular door of some kind with a glass porthole in the middle. Solid-looking hinge mechanisms had a melted appearance. Wheels were circles of crudely cut metal that were twisted and cracked, stuck on axles that were lashed to the hatch with filament. A couple of tarnished boxes lay nearby.

Kysandra didn’t want to look, but couldn’t resist. The wizened body was strange, its skin grey and taut, as hard as stone; wisps of straw-like hair swirled round the skull. Remnants of clothes seemed to be fused with the skin. There was only one boot, on the left foot; the right foot was bare, twisted at an odd angle.

‘Mummified beautifully,’ Nigel said to Fergus as she approached. The two of them were examining the body enthusiastically, poking modules into it. ‘That’s kind of inevitable, given the location.’

‘Is it . . . ?’ Kysandra took a breath, calming herself. ‘Is it human?’