But the day was calm. A couple of her neighbours were chatting over lemonade just a few yards away. She felt safe.

And curiosity burned. This was something new, in the endless unchanging summer of New Springfield. She bent down to peer into the hole in the wall.

Only to find a face looking back out at her.

It was human-sized, but not human. More insectile, she thought, a kind of sculpture of shining black, with a multiple eye like a cluster of grapes. And half of it was coated with a silvery metal, a mask. She saw all this in the heartbeat it took for the shock to work through her system.

Then she yelled, and scrambled back. When she looked again, the masked face was gone.

Josephine Barrow, one of her neighbours, walked over and looked down from above. ‘You OK, honey? Put your spade through your foot?’

‘Can you help me out?’ She raised her arms.

When Cassie was up on the surface, Josephine said, ‘You look like you saw a ghost.’

Well, she’d seen – something.

Cassie looked around at her house, which was almost ready to get its permanent roof put on, and the fields they’d cleared for their crops, and the hole they’d already dug to make a sandpit for their kid to play in some day … All the work they’d put into this place. All the love. She didn’t want to leave this.

But she also didn’t want to deal with whatever the hell was down in that hole.

‘We need to cover this up,’ she said now.

Josephine frowned. ‘After all your work?’

Cassie thought fast. ‘I struck groundwater. No good for a cellar here. We’ll dig a well some day.’ There was a heap of rough-cut timber leaning against the back wall of the house. ‘Help me.’ She started to lay the planks over the hole.

Josephine stared at her. ‘Why not just fill it in?’

Because it would take too long. Because she wanted this hidden for good, before Jeb got back. ‘I’ll backfill it later. For now just help me, OK?’

Josephine was looking at her strangely.

But she helped her even so, and by the time Jeb got back Cassie had spread dirt and forest-floor muck over the timber so you’d never know the hole was there, and had even scraped out the beginnings of a second cellar around the far side of the house.

And by the time they sat down to eat that evening on the porch of their home, Cassie Poulson was well on the way to forgetting she’d ever seen that masked face at all.

And a few years later, in March 2040, Miami, Earth West 4:

It was only a coincidence, historians of the Next would later agree, that Stan Berg should be born in Miami West 4, the Low Earth footprint city where Cassie Poulson had grown up. Cassie Poulson, on whose High Meggers property the primary assembler anomaly proved to be located – an anomaly which, in the end, would shape Stan Berg’s short life, and much more. Strange, but only a coincidence.

Of course, in the very year Stan was born the town began to change dramatically, as the first of a flood of refugees from a Datum America blighted by Yellowstone began to show up. By the time Stan was eight years old an increasingly crowded, lawless and chaotic camp had been taken over by government and corporate interests, and transformed into a remarkable construction site – and by Stan’s eleventh birthday there was a new ‘star’ in the sky, stationary above the southern horizon – not a true star, but the orbital terminus of a nascent space elevator that reached down to the local version of Florida, built by a community of hastily recruited stalk jacks that by then included Stan’s own mother and father.

But whatever the convulsions that would colour Stan’s young life, there was nothing strange about the love that filled Stan’s mother Martha from the moment she first held her child. And she, at least, saw nothing strange in the apparent curiosity with which, eyes precociously open, Stan inspected the changing world from the moment he was delivered into it.

Joshua Valienté was always sceptical about Bill Chambers’s Joker stories. But, he would realize in retrospect, if he’d paid more attention and thought a little more deeply about what Bill was saying, he might have got some earlier clues into the meaning of it all. Such as what Bill told him in 2040 – the same year Stan Berg was born – as he travelled with Joshua in an airship into the High Meggers far beyond New Springfield, a story about a Joker he called the Cueball:

Joshua had actually glimpsed this Joker himself. He and Lobsang had in fact discovered it, nestling in that band of relatively domesticated worlds called the Corn Belt, on their first journey out into the deep Long Earth, during which Joshua had first learned the meaning of the word. ‘Jokers,’ Lobsang had said. ‘Worlds that don’t fit the pattern. And there is a pattern, generally speaking. But the broad patterns are broken up by these exceptions: Jokers in the pack, as scholars of the Long Earth call them …’ Joshua already knew many such worlds, even if he’d had no name for the category. This Joker had been a world like a pool ball, an utterly smooth, colourless ground under a cloudless deep blue sky.

But even though he’d seen the place for himself Joshua knew better than to take Bill’s stories at face value. Bill Chambers, about Joshua’s age, had grown up alongside him at the Home in Madison, Wisconsin. He’d been a friend, a rival, a source of trouble – and always a consummate liar.

Bill said now, ‘I know a fella who knew a fella—’

‘Oh, yes.’

‘Who camped out on the Cueball for a bet. Just for a night. All alone. As you would. In the nip too, that was part of the bet.’

‘Sure.’

‘In the morning he woke up with a hangover from hell. Drinking alone, never wise. Now this fella was a natural stepper. So he got his stuff together in a blind daze, and stepped, but he says he sort of stumbled as he stepped.’

‘Stumbled?’

‘He didn’t feel as if he’d stepped the right way.’

‘What? How’s that possible? What do you mean?’

‘Well, we step East, or we step West, don’t we? You have the soft places, the short cuts, if you can find them, but that’s pretty much it …’

Stepping: on Step Day the world had pivoted around mankind. Suddenly, in return for the effort of building a Stepper box, a crude electrical gadget – and some, like Joshua, didn’t even need that – you could step sideways out of the old reality, out of the world and into another, just like the original yet choked with uncleared forest and replete with wild animals – for it was only in the original Earth that mankind had evolved, and had had a chance to shape its world. Whole planets, a short walk away. And, in either direction, East or West, you could take another step, and another. If there was an end to the Long Earth, as the chain of worlds became known, it was yet to be found. After Step Day everything had been different, for mankind, for the Long Earth itself – and, in particular, for Joshua Valienté.

But even the Long Earth had its rules. Or so Joshua had always thought.

‘… Anyhow this fella felt like he’d stepped a different way. Perpendicular. Like he’d stepped North.’

‘And?’

‘And he emerged on to some kind of other world. It was night, not day. No stars in the clear sky. No stars, sort of. Instead …’

‘Your storytelling style really grates sometimes, Bill.’

‘But I’ve got ye hooked, haven’t I?’

‘Get on with it. What did he see?’

‘He saw all the stars. All of them. He saw the whole fecking Galaxy, man, the Milky Way. From outside.’

Outside the Galaxy. Thousands of light years from Earth – from any Earth …

Bill said, ‘Still in the nip he was, too.’

That was the trouble with combers, Joshua had concluded. They were just expert bullshitters. Maybe they spent too much time alone.

But, he realized, reflecting in February 2052, he’d tended to think even of Lobsang as a bullshitter, albeit a shitter built on a truly cosmic scale. If only he’d listened to Lobsang when he’d had the chance.