Kate grabbed Bobby by his good arm and hauled him, by main force, over the threshold of the bunker. He cried out as his head hit on the door’s thick metal sill, but she ignored him.

As soon as his dangling feet were clear she slammed the door, masking the rising noise of the wormhole, and began to dog it shut.

Hiram’s security goons were approaching, bewildered. Kate, hauling on the wheel, screamed at them. “Help him up and get out of here!”

But then the wall bulged out at her, and she glimpsed light, as bright as the sun. Deafened, blinded, she seemed to be falling.

Falling into darkness.

As two stapledons, disembodied WormCam viewpoints, Bobby and David soared over southern Africa.

It was the year 2082. Four decades had elapsed since the death of Hiram Patterson. And Kate, Bobby’s wife of thirty-five years, was dead.

A year after he had accepted that brutal truth, it was never far from Bobby’s thoughts, no matter what wonderful scenery the WormCam brought him. But he was still alive, and he must live on; he forced himself to look outward, to study Africa.

Today the plains of his most ancient of continents were covered with a rectangular gridwork of fields. Here and there buildings were clustered, neat plastic huts, and machines toiled, autonomous cultivators looking like overgrown beetles, their solar-cell carapaces glinting. People moved slowly through the fields. They all wore loose white clothes, broad-brimmed hats and gaudy layers of sunblock.

In one farmyard, neatly swept, a group of children played. They looked clean, well dressed and well fed, running noisily, bright pebbles on this immense tabletop landscape. But Bobby had seen few children today, and this rare handful seemed precious, cherished.

And, as he watched more closely, he saw how their movements were complex and tightly coordinated, as if they could tell without delay or ambiguity what the others were thinking. As, perhaps, they could. For he was told — there were children being born now with wormholes in their heads, linked into the spreading group minds of the Joined even before they left the womb.

It made Bobby shudder. He knew his body was responding to the eerie thought, abandoned in the facility that was still called the Wormworks — though, forty years after the death of Hiram, the facility was now owned by a trust representing a consortium of museums and universities.

So much time had elapsed since that climactic day, the day of Hiram’s death at the Wormworks — and yet it was all vivid in Bobby’s mind, as if his memory were itself a WormCam, his mind locked to the past. And it was now a past that contained all that was left of Kate, dead a year ago of cancer, her every action embedded in unchangeable history, like all the nameless billions who had preceded her to the grave.

Poor Hiram, he thought. All he ever wanted to do was make money. Now, with Hiram long dead, his company was gone, his fortune impounded. And yet, by accident, he changed the world… David, an invisible presence here with him, had been silent for a long time. Bobby cut in empathy subroutines to glimpse David’s viewpoint.

…The glowing fields evaporated, to be replaced by a desolate, arid landscape in which a few stunted trees struggled to survive.

Under the flat, garish sunlight a line of women worked their way slowly across the land. Each bore an immense plastic container on her head, containing a great weight of brackish water. They were stick-thin, dressed in rags, their backs rigid.

One woman led a child by the hand. It seemed obvious that the wretched child — naked, a thing of bones and papery skin — was in the grip of advanced malnutrition or perhaps even AIDS: what they used to call here, Bobby remembered with grim humour, the slims disease.

He said gently, “Why look into the past, David? Things are better now…”

“But this was the world we made,” David said bitterly. His voice sounded as if he were just a few metres away from Bobby in some warm, comfortable room, rather than floating in this disregarded emptiness. “No wonder the kids think we old folk are a bunch of savages. It was an Africa of AIDS and malnutrition and drought and malaria and staph infections and dengue fever and endless futile wars, an Africa drenched in savagery… But,” he said, “it was an Africa with elephants.”

“There are still elephants,” Bobby said. And that was true: a handful of animals in the zoos, their seed and eggs flown back and forth in a bid to maintain viable populations. There were even zygotes, of elephants and many other endangered or otherwise lost species, frozen in their liquid nitrogen tanks in the unchanging shadows of a lunar south pole crater — perhaps the last refuge of life from Earth if it proved, after all, impossible to deflect the Wormwood.

So there were still elephants. But none in Africa: no trace of them save the bones occasionally unearthed by the robot farmers, bones sometimes showing teeth marks left by desperate humans. In Bobby’s lifetime, they had all gone to extinction: the elephant, the lion, the bear — even man’s closest relatives, the chimps and gorillas and apes. Now, outside the homes and zoos and collections and labs, there was no large mammal on the planet, none save man.

But what was done was done.

With an effort of will Bobby grasped his brother’s viewpoint and rose straight upward.

As they ascended in space and time the shining fields were restored. The children dwindled to invisibility and the farmland shrank to a patchwork of detail, obscured by mist and cloud.

And then, as Earth receded, the bulbous shape of Africa itself, schoolbook-familiar, swam into Bobby’s view.

Farther to the west, over the Atlantic, a solid layer of clouds lay across the ocean’s curving skin, corrugated in neat grey-white rows. As the turning planet bore Africa toward the shadow of night, Bobby could see equatorial thunderheads spreading hundreds of kilometres toward the land, probing purple fingers of darkness.

But even from this vantage Bobby could make out the handiwork of man.

There was a depression far out in the ocean, a great cappuccino swirl of white clouds over blue ocean. But this was no natural system; it had a regularity and stability that belied its scale. The new weather management functions were, slowly, reducing the severity of the storm systems that still raged across the planet, especially around the battered Pacific Rim.

To the south of the old continent Bobby could clearly see the great curtain-ships working their way through the atmosphere, the conducting sheets they bore shimmering like dragonfly wings as they cleansed the air and restored its long-depleted ozone. And off the western coast pale masses followed the line of the shore for hundreds of kilometres: reefs built up rapidly by the new breed of engineered coral, labouring to fix excess carbon — and to provide a new sanctuary for the endangered communities of plants and animals which had once inhabited the world’s natural reefs, long destroyed by pollution, over-fishing and storms.

Everywhere, people were working, repairing, building.

The land, too, had changed. The continent was almost cloud free, its broad land grey-brown, the green of life suppressed by mist. The great northern mass which had been the Sahara was broken by a fine tracery of blue white. Already, along the banks of the new canals, the glow of green was starting to spread. Here and there he could see the glittering jewel-like forms of PowerPipe plants, the realization of Hiram’s last dream, drawing heat from the core of Earth itself — the energy bounty, free and clean, which had largely enabled the planet’s stabilizing and transformation. It was a remarkable view, its scale and regularity stunning; David said it reminded him of nothing so much as the old dreams of Mars, the dying desert world restored by intelligence.