‘OK, ColU, I believe you.’ Yuri looked around, trying to imagine it. ‘So here was some kind of community of builders. They built a sun-catcher plant, and other facilities, with a technology far in advance of anything they have now. This was so long ago that barely anything remains of their work here. Civilisation fell, right?’

‘I would not jump to conclusions,’ the ColU said.

‘They were gathering stellar energy. To do what?’

‘To make something even more exotic,’ Mardina guessed.

‘Yes,’ said the ColU. ‘Obviously you have the evidence in front of you, in the shape of the hatch, exotic compounds in the soil. It is strange, to just find this one site. Granted we have hardly surveyed the planet comprehensively, but you would imagine that a high-technology culture would have left traces of their passing everywhere, not just this one installation . . .’

Tollemache grunted. ‘Wait until they get some real scientists down here, and then you might get some decent answers. Not from this glorified tractor.’

The ColU dropped its sensor pod towards the ground, as if bowing in submission. ‘I can’t argue with that, Colonel. I am not equipped for this manner of work, not in a specialised way.’

Now Beth spoke, for the first time since arriving here. ‘What, are you saying we should wait around for eight years, and grow old and probably, like, die before anybody does anything about this?’

Yuri had to smile. ‘So what would you suggest?’

Beth gestured. ‘We open the hatch, obviously.’

Mardina said, ‘But there’s two problems with that, honey. One is that it doesn’t lead anywhere. You heard what the ColU said. There’s nothing underneath.’

Yuri said, ‘Maybe, but she’s right. This is obviously a hatch. What do you do with a hatch, but open it?’

‘OK,’ said Mardina with strained patience, ‘but that raises my second problem. How do we open it? Do you see anything like a handle? A wheel to turn, a combination lock to try?’

‘Yes,’ Beth snapped immediately. She walked onto the hatch, to one of the starburst indentations. ‘Look at these grooves. Three of them, each, what, a bit less than a metre long? And this fat indentation in the centre. Can’t you see what they’re for? Look, suppose I was a builder . . .’

And she lay down on her back over one of the groove sets, with her arms held out at two o’clock and ten o’clock, and her legs together at six o’clock.

‘Shit, she’s right,’ Tollemache murmured.

‘These little cuttings are meant to hold builders,’ Beth said. ‘Count them. Nine cuttings in this surface, all inside the seam. You think it’s a coincidence that nine builders showed up here today? They know what to do. We just have to get out of the way.’

‘Wait,’ Mardina said. She walked forward, as if trying to block the builders off. ‘Are we sure we want to do this? We don’t know what we’re dealing with here. We don’t know what danger this represents.’

Tollemache took a step backwards. ‘That’s true. Your tractor over there talked about huge energies being deployed. What if it’s a bomb? A booby trap of some kind?’

Yuri sneered. ‘Who would build a booby trap like this, and leave it in the ground for centuries?’

The ColU said, ‘The structure is many orders of magnitude older than mere centuries, Yuri Eden.’

‘Not a bomb,’ Mardina said. ‘Something else. Something stranger. My head’s swimming, Yuri. Strangeness upon strangeness. This thing was intentionally left here by somebody, builders or not, for some purpose. We’ve no idea what that purpose was. We’ve got no reason to believe it’s likely to be in any way in our interest. We shouldn’t even be here. Humans on this planet, I mean.’

Beth walked up and took her hands. ‘Mom. You’re freaking me out. But you need to stop protecting me. I’m twenty years old. I can make my own decision.’

Yuri felt an echo of Mardina’s alarm, but he said, ‘So what is your decision?’

‘We open the hatch. Of course we open it. Anything else is going to drive me crazy, for the rest of my life!’

Tollemache cackled. ‘You’re outvoted, I’d say, Jones.’

‘Well, we all are,’ said the ColU, untroubled.

‘Who by?’

‘The builders.’

And Yuri saw that the nine builders were already making their way towards the hatch cover, and their engraved beds. They moved in the usual builder way, spinning and clattering, like eerie stringless puppets, but their motions were purposeful, even coordinated, as if each one seemed to know which of the shallow cuttings to pick. Quietly, the nine of them settled into the engraved slots. Which, as Yuri saw, as Beth had first noticed, fit them perfectly.

The ground under their feet shuddered, as if some vast engine had been woken.

And puffs of dirt rose up from the circular seam around the hatch.

CHAPTER 57

Mardina grabbed Beth and Yuri by the hand and pulled them away. ‘Back,’ she said. ‘You too, ColU.’ She ignored Tollemache, but Yuri saw that the Peacekeeper was stepping back too, keeping his sensor pack trained on the hatch.

And then, with a deeper shudder in the earth, the hatch lifted. It tipped up, as if it was hinged at a point to Yuri’s left, opening like a lid, slow, ponderous. The builders, evidently living keys in the hatch’s multiple lock, stayed motionless, held in position somehow so they did not fall, even as the hatch approached the vertical. The hatch’s position obscured Yuri’s view of whatever lay beneath the lid, but he saw that light poured out, a pale, pearly glow that underlit the branches of the nearby trees. And he felt a gush of cooler air, coming from beneath the hatch.

Somewhere a kite took off, startled.

When the hatch was vertical, it stopped moving. It was a tremendous, evidently massive disc, resting on its edge, invisibly hinged.

Tollemache, his recorder pack held before him like a weapon, was the first to walk forward. The brilliant light from the ground underlit his jowly face. ‘Holy shit,’ he said. ‘You’d better come and see this. Step carefully now.’

The rest walked around the open lid. Beth asked, ‘Carefully in case of what?’

‘In case you fall in.’

Somehow it was no surprise at all for Yuri to discover that beneath the opened hatch was a pit, a simple cylinder with plain walls and a flat floor, perhaps four metres deep. The light came from no particular source; rather the walls and floor all glowed with that grey-white light. One part of the wall was broken by what was evidently another hatch, a fine circular seam, with a set of groove-locks to hold just three builders this time. On the wall opposite that was some kind of adornment, what looked like a tapestry made out of stem-bark cloth.

And it didn’t surprise him either that three of the builders now hopped out of their grooves on the hatch and swarmed down into the pit, clinging somehow to the sheer walls. Once down they began to spin and turn on the floor, joyously.

The ColU cautiously extended its sensor pack. The four humans peered down, their faces lit from below.

‘It’s real, then,’ Mardina said. ‘I mean, it’s a real hole in the ground, not some kind of visual trick. Given that the builders have climbed down inside it.’

‘Impossible,’ said the ColU flatly. ‘My geophysical results were conclusive. There is no hole here. There cannot be.’

‘Yet here it is,’ Yuri said.

‘Maybe I didn’t stamp hard enough,’ Beth said mischievously.

‘No, it wasn’t that. My analysis—’

‘I’m teasing you!’

Yuri said, ‘We’ll have trouble climbing back up from that.’

‘I got a ladder in the rover.’ Tollemache went to fetch it.

‘Hold on,’ Mardina said. ‘Just hold on. Climbing back up? Are you seriously intending to climb down there? Into that impossible hole?’

Beth looked at her mother. ‘Sure. What else?’