She felt her temperature rising, and she was aware of the cat’s eyes on her, a silent warning. ‘Captain, it’s November in a leap year. This is the time we hold a presidential election. It’s what we do in America, supervolcano or not. I – we – do appreciate all the Chinese government is doing to help us out in this situation. But—’

‘Ah, but you don’t welcome my comments on your internal affairs, do you? Perhaps you’ll have to get used to that, Captain Kauffman.’ He gestured at the tablet on her desk. ‘I’m sure your latest projections match our own, concerning the future of your country. It seems likely that twenty per cent of the continental Datum USA will eventually be abandoned altogether, a swathe spanning Denver, Salt Lake City, Cheyenne. Eighty per cent of the rest is under ash thick enough to disrupt agriculture. While the evacuation flow to the stepwise worlds has been intense, still many millions remain on the Datum, and stores of food and water are rapidly diminishing – as they are even in stepwise holding areas like this, are they not? And during this winter many will starve without gifts of, for example, Chinese rice, delivered stepwise by twain, or by freighters crossing the Datum seas. You are dependent on the rest of the world now, Captain Kauffman. Dependent. And I doubt that will change any time soon.’

She knew he was right. Her own advisers among her crew on the twain were telling her that the volcano was now having global effects, effects that were going to linger. The ash had washed out fairly quickly – though even lying on the ground it remained a problem, as Chen had said – but sulphur dioxide from the eruption was hanging around in the air as aerosol particles, creating terrific sunsets but deflecting the sun’s heat. As the Datum headed into its first post-volcano winter, temperatures had plummeted fast and early, and spring next year was going to be late, if it showed up at all.

Yes, America would need Chinese rice for the foreseeable future. But Maggie could see that the challenge was going to be to stop ‘friends’ like China using the disaster to gain a permanent foothold in American society. Already there had been rumours that the Chinese were running tobacco into a nicotine-starved Datum America – like the Opium Wars in reverse, she thought.

Maggie Kauffman, however, worked on the principle of dealing with the practical problems before her, and letting the wider world take care of itself.

‘About your ballot boxes, Captain Chen. Suppose I assign a small team of my own crew to travel with you until the election is over. They can take authority for the operation – as well as responsibility for any errors.’

He smiled broadly. ‘A wise solution.’ He stood up. ‘And I wonder if I could send over a detachment of my own crew, in the spirit of cultural exchange. After all, our governments are already discussing sharing twain technology, for example.’ He glanced around dismissively. ‘Our own ships being somewhat more advanced than your own. Thank you for your time, Captain.’

When he’d gone, Maggie murmured, ‘Glad that’s over.’

‘Quite,’ said Shi-mi.

‘Listen. Remind me to tell the XO to sweep this “exchange crew” from toenails to eyebrows for bugs and weapons.’

‘Yes, Captain.’

‘And smuggled cigarettes.’

‘Yes, Captain.’

In the sidpa bardo, said some versions of the Bardo Thodol, the spirit was given a body superficially like the former physical shell, but endowed with miraculous powers, with all sense faculties complete, and the capability of unimpeded motion. Karmic miraculous powers.

Thus the vision of Lobsang embraced the world – all the worlds. Sister Agnes would probably ask if his soul was flying high above the ground.

And, thinking of Agnes, Lobsang looked down on an unprepossessing children’s home in a stepwise copy of Madison, Wisconsin, in May 2041, half a year after the eruption . . .

As that bad first winter gave way to a desolate spring, and America entered a long period of post-Yellowstone recovery, newly re-elected President Cowley announced that the nation’s capital was to be, pro tem, Madison West 5, replacing an abandoned Datum DC. And he was going to deliver a big speech to inaugurate the city into its new role from the steps of this world’s version of the Capitol building, a big barn of timber and blown concrete that was a brave imitation of its long-destroyed Datum parent.

Joshua Valienté was sitting in the parlour of the Home, staring at TV images of an empty presidential podium. He was here ostensibly to visit with fifteen-year-old Paul Spencer Wagoner, an extremely bright and extremely troubled kid who Joshua had first encountered in a place called Happy Landings, many years ago. Joshua had been instrumental in getting Paul into the Home after his family broke up. But Paul was out right now, and Joshua couldn’t resist tuning in to the sight of a President, in Madison.

Cowley bounced up on to the stage, all teeth and hair, under a rippling Stars and Stripes – the new holographic version of the flag, enhanced to reflect the reality of the nation’s stepwise extension into the Long Earth.

‘I’m amazed he’s actually here,’ Joshua said to Sister John.

Sister John, born Sarah Ann Coates and once, like Joshua, a resident of the Home on Allied Drive in Datum Madison, now ran this relocated institution. Her habit was as always clean and pressed. Now she smiled and said, ‘Amazed at what? That the President chose Madison for the new capital? It is about the most mature city in the Low Americas.’

‘Not just that. Look who’s up there on the stage with him. Jim Starling, the Senator. Douglas Black.’

‘Hmmph,’ said Sister John. ‘They should have invited you. As a local celebrity. As cheeseheads go, you’re famous: Joshua Valienté, hero of Step Day.’

Step Day, when every kid in the world had built a Stepper box and immediately got lost in the forests of wild parallel worlds. In the vicinity of Madison it had been Joshua who had brought the lost children home – including Sarah, now Sister John.

Joshua said ruefully, ‘I always kind of hope people have for gotten. Anyway they’d probably kick me off the podium because I’m so grimy. Damn ash, no matter how hard I scrub I can never get it out of my pores.’

‘Still going back to the Datum on rescue missions?’

‘We are going back, but there’s nobody left to rescue. Now we’re reclaiming stuff from the abandoned zone close to the caldera, across Wyoming, Montana, the Rocky Mountain states. It’s surprising what’s survived: clothing, gasoline, canned food, even animal feed. And we bring out anything technical that looks usable. Cellphone masts, for instance. Stuff we’ll need for the recovery efforts in the Low Earths. Most of the workers are impressed labour from the refugee camps.’ He grinned. ‘They fill up their pockets with any money they find. Dollar bills.’

Sister John snorted. ‘Given the way the economy’s tanked and the markets have crashed, those bills would be more useful burned to keep warm.’

He made to reply, but she shushed him as Cowley began his speech.

After a routine opening, all welcome and wisecracks, Cowley summed up the situation of America and the Datum world, eight months after the eruption. As winter turned to spring, things weren’t getting any better. The global climatic effects had locked in. The monsoon rains in the Far East had failed last fall. Since then, pretty much everywhere across the world north of the latitude of Chicago – Canada, Europe, Russia, Siberia – had endured the most savage winter anybody could remember. Now a matching calamity was already unfolding below the equator as the southern-hemisphere winter arrived.

All of which meant that a new world had to be planned for.

‘Well, now, we got through this first winter living off the fat of the past – of the pre-volcano days. We can’t afford to do that no longer, because it’s all – used – up.’ Cowley emphasized that with hand-chops on his podium. ‘And nor can we rely on food imports from our neighbours and allies, who have been more than generous so far, but who have their own problems, this cold summer. And hey, Uncle Sam feeds himself. Uncle Sam looks after his own!’