‘Would that be so surprising? Consider all that I’ve achieved in my life. As I reach my twilight years, can you not believe that I would want to buy myself such final adventures as this? Think, Captain. We have all become rather blasé about the Long Earth, the tremendous higher-dimensional landscape into which we are so boldly striding. And yet, are there not deeper mysteries of existence? Maybe it’s not so strange that a quarter-billion worlds exist for us to explore in this marvellous ship of yours. What’s strange is that even one world should exist . . . As to what we might find out there: who knows? How could I not go on such a mission, if I have the chance? And I must go now, before I depart the universe myself, all too soon.’

‘Oh, come on, Mr Black, I don’t buy any of that. You’re no tourist; you have come aboard with some specific goal.’

‘Ha!’ He clapped his hands, seeming pleased. ‘I always knew you were a bright one. Very well, then. What do you think I hope to achieve?’

‘How should I know? I didn’t even know you were on this ship until an hour ago. Perhaps you’re seeking the fountain of youth.’

He raised silver eyebrows. ‘You are surprisingly perceptive. I should say no more. There is something specific I’m looking for, and if we find it, I’ll know immediately. Now.’ He began to clamber out of his seat, cautiously; the bodyguard, Philip, lent a hand. ‘You mustn’t feel you have to make a fuss of me.’

‘Believe me, sir, I don’t. This is a military ship. You are cargo. And superfluous cargo at that.’

‘Well. That’s an upgrade from stowaway class, at least. But now that I’m out of the brig, so to speak, I wonder if I could see something of your fine ship. Perhaps I could borrow your charming Executive Officer for an hour or so.’

‘I don’t see why not. I’ll also put Mac, I mean my ship’s surgeon, Doctor Mackenzie, in touch with you, to ensure your physical condition is taken care of.’

‘That won’t be necessary, I assure you. As I said, I have my own physician—’

‘That wasn’t optional, sir. This is my ship. I’m responsible for your safety, now I know you’re aboard. Mac will see you tomorrow.’

‘Then I shall look forward to it. Where, if I may ask, is our next stop to be?’

She could answer that precisely. ‘Aside from a few test stops, Earth West 1,617,524. Be there in a few days. Where we’ll be picking up another crew member.’ And, she thought with dismay, another set of personnel problems for her. But at least it was her choice this time.

‘Perhaps I will have the chance to stretch my legs there.’

‘Mr Black, as far as I’m concerned you won’t be setting foot off this ship until she’s back in dry dock.’

Black laughed. ‘I do admire your straightforward approach, Captain Kauffman. Farewell for now. Come, Philip . . .’

8

SISTER AGNES WAS RIGHT. Joshua was reluctant to jump when Lobsang called. He’d never really got over Lobsang’s failure to save Datum Madison from a terror attack, a nuclear weapon, back in 2030. And, deeper than that, he’d never felt comfortable at how Lobsang, beginning over fifteen years ago already, had ensnared Joshua, a natural loner, in his plans and schemes.

But on the whole, he had to admit, Lobsang had been a force for good, in the Long Earth. Maybe now he was trying to be a force for good again.

Also, according to Agnes, Lobsang was lonely.

And then there was the headache. As he’d become aware of this warning sign inside his own cranium, for sure a sign of some kind of disturbance across the Long Earth, Joshua had been expecting some kind of contact from Lobsang. He was almost relieved when it came.

What the hell. Back to the Datum he went.

Joshua agreed to meet Lobsang in the town of Twin Falls, Idaho, Datum Earth, around a hundred and fifty miles from Yellowstone.

For Joshua, just stepping into the town was problematic now. The ice and the ash on the Datum ground meant that the standing surface was far from the level of the neighbouring stepwise worlds, and unpredictable. So Joshua stepped back to the Datum a respectable distance from Twin Falls, hired an SUV, and drove in.

The roads were open, just, especially the freeways and interstates. There was little traffic save for heavy trucks and a few buses, with bundled-up people sitting behind steamed-up windows: very few private vehicles on the road, few cars like his own SUV, and you could blame the worldwide shortage of gasoline for that.

It went well at first. Then he got caught in a blizzard. He had to follow a heavy snow plough for miles.

When he finally reached Twin Falls, he found it basically frozen. The roads were flanked by ice, old, dirty, layered ice, ice that had already endured for years, ice like you might find on the north pole of Mars, he imagined. And in with the ice was volcano ash, even out here, years after it had stopped falling from the sky, heaps of it swept into corners or consolidated by the ice into hard, gritty banks by the road. Right into the centre of town properties had collapsed from falls of ash or snow, some of them burned out. None of these had been reconstructed, or cleared. This was Idaho, in January. It was like Ice Age worlds he’d visited.

He wondered why people were bothering to stay here at all – and he knew that in fact there were still a few inhabited communities even further north than this. Stubbornness, he supposed, sheer inertia. Or pride: humans, he had observed, had a way of rising to a challenge, refusing to be beaten no matter how overwhelming the odds, returning to their homes on the floodplain when the water receded, to the flanks of the volcano once the eruption was over. Twin Falls was still liveable, just, and so people still lived here, in their homes.

He left his SUV in a motel’s parking lot, having agreed upfront a payment for the innkeeper to watch over the vehicle for him until he returned. The innkeeper advised him to siphon out his gasoline before leaving the car, and then tried to dicker over the price they’d fixed. The guy got short shrift from an ill-tempered Joshua, whose weeks-long High Meggers headache had only worsened as he’d come back in to the Datum.

He was a little early for his appointment with Lobsang, so he walked into the centre of town and bought a coffee, paying an astounding price for what tasted like scrapings diluted with sawdust. But at least he got to sit in the muggy warm of the mom-and-pop coffee shop while he waited.

And, after an hour, bang on time, a twain came swimming into the murky sky.

They seemed to have remarkably little to say to each other, face to face, as Lobsang welcomed Joshua on board. Joshua focused on the twain itself.

At two hundred feet long this airship was a small one, compared with Lobsang’s own Mark Twain, and the mighty commercial ships of the Long Mississippi. Its gondola was no larger than a travel trailer. But, Joshua realized as Lobsang showed him around, the gondola was comfortable enough for two. It had a roomy lounge with expansive windows, and airline-type couches, a galley, a small table, and wall-mounted tablets with animated map displays and readings of altitude, windspeed, temperature.

As on all Lobsang’s airships there were private quarters behind closed doors – machine shops for maintaining Lobsang’s artificial infrastructure, tucked neatly out of sight, Joshua had always supposed. But through one half-open door Joshua glimpsed an upright cylinder, maybe three feet tall, intricately etched – a prayer wheel? And behind that a kind of shrine, a golden Buddha in an ornate setting of red and green and gold leaf. A whiff of incense. Another part of Lobsang, Joshua supposed, that was hidden from general view.

There was an earthometer, though Lobsang had warned Joshua that his plan was not to travel stepwise today but to journey across the Datum Earth. They would follow the interstates, the 84, 86 and 15, more or less north and east, and go take a look at the new Yellowstone caldera.