Now, in a stir of excitement, the technicians and scientists gathered closer around the TV monitors and tablets. The live images were clearing up, as if a snowstorm were fizzling out. Sally saw the flank of a stubby aircraft sitting on a surface of what looked like wet ruddy sand, like a beach revealed by a recently receding tide. The camera must be mounted on the aircraft itself; she could clearly see the Stars and Stripes boldly painted on its hull.

And then the camera panned away from the aircraft to reveal a glimpse of a shallow valley, with a river running, and tough-looking grey-green vegetation clumped on the banks. A living Mars.

The Poindexter types whooped and cheered.

They retired to a small coffee bar.

Sally faced her father. ‘All right, Dad, enough of the space trophies and the enigmatic remarks. In no particular order—’ She counted the points on her fingers. ‘Tell me why you want to go to Mars. And how you’re going to get there. And why under all the heavens I would want to go with you.’

He eyed her shrewdly. He was seventy years old now, and the wrinkled skin of his face looked tough as leather. ‘It’ll take a while to explain. Here’s the headline. I want to go to this Mars, the Mars of the Gap, because it’s not just Mars. It’s not even just a Mars with a significantly different climate. It’s a Long Mars.’

She took that in. ‘You said that before. Long Mars. You mean you can step there?’

He nodded curtly.

‘How do you know? . . . No, don’t answer that.’

‘There’s something specific I’m looking for, and expecting to find. You’ll see. But for now – the most important thing is, if a world is Long, then it must harbour sapience. Intelligent life.’ He looked at her. ‘You understand that much, don’t you? The theory of the Long Earth, the interfacing of consciousness and topology—’

Her jaw had dropped. ‘Hold on. Back up. You just dropped another conceptual bomb on me. Intelligent life? You discovered intelligent life on Mars?’

He was impatient. ‘Not on Mars. On a Mars. And, not discovered. Deduced the necessary existence of. You always were a sloppy thinker, Sally.’

Needled, her instinct was to fight back, as it had been since she’d been old enough to need to establish her own identity. She said provocatively, ‘Mellanier wouldn’t agree with you. About sapience and the Long Earth, that a Long world is somehow a product of consciousness.’

He waved a hand dismissively. ‘Ah, that fraud. As to why you might go with me to explore – well, why the hell wouldn’t you?’ He glanced around at the geeks in the coffee bar, noisily celebrating their triumph. ‘Look at these back-slapping Brainiacs. I do know you, Sally. You liked it best before Step Day, when the Long Earth was just ours, right? Long Wyoming was, anyhow. Before I came up with the Stepper box I couldn’t step myself, I needed you to take me over, but—’

‘You’d read to me. Stories of other worlds, of Tolkien and Niven and E. Nesbit, and I’d pretend that was where we were going . . .’ She shut up. Nostalgia always felt like a weakness.

‘And now it’s all cluttered up by yahoos like these. No offence, Al.’

‘None taken.’

‘Sally, I know you still spend a lot of time alone. Wouldn’t you like to get away to a new world, a raw world, empty except for us – well, us, and a few Martians? Leave humanity behind for a while . . .’

And Lobsang, she thought.

Raup leaned forward, sweaty, intrusive. ‘As to how we’d get there, maybe you can already tell that the space programme we’re running out of this place is developing a hell of a lot faster than the plod back on Earth. Of course we’re able to build on all they learned and reapply it—’

‘Get to the point, propeller-head.’

‘The point is we’re ready to go. The first manned spacecraft to Mars. It’s waiting at the Brick Moon, just one step away, in the Gap. We wanted to wait until we got confirmation of the planet’s atmospheric conditions and so on from these automated landers. But now that we’ve got that—’

‘We? Who exactly is going on this mission?’

Raup puffed out his chest and lifted his hefty belly. ‘Our crew will be three, just like the Apollo missions. Yourself, your father, and me.’

‘You.’

Willis put in, ‘I know what you’re thinking. But you and I aren’t astronauts, Sally—’

‘Nor is this puff-ball. Dad, there’s no way I’m spending months in a tin can with this guy.’

Willis seemed unperturbed. ‘You have an alternative?’

‘Does a guy called Frank Wood still hang around here?’

3

WOULD FRANK WOOD TAKE a ride to Mars?

In 2045, Francis Paul Wood, USAF (retired), was sixty-one years old. And flying in space had been his dream since boyhood.

As a kid he’d been an odd mix of sports jock, engineering hobbyist and dreamer. He was encouraged by his parents, and an uncle who wrote about the space programme and loaned him a library of old science fiction, from Asimov to Clement and Clarke and Herbert. But by the time his dreams started to take realistic shape, the Challenger crash was already history, a disaster that had happened before he was two years old.

Still, he’d progressed. Once he’d been a NASA candidate astronaut, a career development after active service in the Air Force; he’d got that close. Then came Step Day, when an infinity of worlds had opened up within walking distance of an unequipped human, and spaceships had become instant museum pieces. And so had Frank Wood, it felt like, at thirty-one years old. He had become restless, nostalgic, and without a close family, having sacrificed relationships for a dream of a career. Suddenly he found that he’d become the uncle with the connections to the space programme and a trunk full of science fiction novels.

Burdened by a sense of opportunities lost, he’d spent some years hanging around what remained of Cape Canaveral, doing whatever work he could find. But Canaveral, aside from a continuing programme of launches of small unmanned satellites, was little more than a decaying museum of dreams.

And then had come the discovery of the Gap, a place where a conjunction of cosmic accidents had left a hole in the chain of worlds that was the Long Earth, and a new kind of access to space. A few years after that Frank, by then in his fifties, had gone out there to find a bunch of kids and young-at-heart types busily building an entirely new kind of space programme, based on an entirely new principle. Frank had thrown himself into the project with enthusiasm, and liked to think he injected a modicum of wisdom and experience into what had felt, in those early days, like some kind of ongoing science fiction convention, and these days more like the Gold Rush.

When Yellowstone had blown up back on the Datum, Frank, with many others – including a new friend called Monica Jansson, whom he’d met when Sally Linsay had come here to rescue abused trolls, as she’d seen it – had put aside his own projects and had travelled home to help. Well, Monica was long dead now, and the Datum was kind of settling down to a new equilibrium – or at least people had stopped dying in such numbers as they had been – and Frank felt entitled to go back to his own set-aside dreams. Back to the Gap.

And now here was Sally Linsay in his life again, and her father, with a startling proposition for him.

Would Frank Wood take a ride to Mars? Hell, yes.

They got to work.

4

OUTSIDE MADISON WEST 5, at an unprepossessing workshop belonging to a wholly owned subsidiary of the Black Corporation, Lobsang – or rather an ambulant unit, one incarnation of Lobsang – worked on a service of Sister Agnes’s Harley. He was convincing at it too as he tinkered, his sleeves rolled up, oil smeared on his hands and forehead and grubby old overalls, even as he lectured Agnes on the state of the worlds in a rather rambling way.