Even as he turned his head from side to side, it was impossible to grasp the full scale of the structure. At times it seemed close enough to touch, like a giant dynamic wall-sculpture he might reach into and explore. And then it would recede, apparently to infinity. He knew his imagination, evolved to the thousand-kilometre scale of Earth, was inadequate to the task of grasping the immense distances involved here.

For if the sun was moved to the centre of the nebula, humans could build an interstellar empire without reaching the edge of the cloud.

Wonder surged in him, sudden, unexpected. I am privileged, he thought anew, to live in such a time. One day, he supposed, some WormCam explorer would sail beneath the icy crust of the moon and seek out whatever lay at its core; and perhaps teams of investigators would scour the surface of the planet below, seeking out relics of the past.

He envied those future explorers the depth of their knowledge. And yet, he knew, they would surely envy his generation most of all. For, as he sailed outward with the expanding front of WormCam exploration, David was here first, and nobody else in all of history would be able to say that.

Long story. Japanese lab. The place he used to clone tigers for witch doctors. Heather just a surrogate. David WormCammed it all. Then all that mind control. Hiram didn’t want more mistakes…

Heather. I felt no bond. Know why now. How sad.

She thought she could feel his pulse in the invisible touch at her palm. Yes sad sad.

And then, without warning, the door crashed open. Mae Wilson walked in holding a pistol. Without hesitation she fired once, twice, to either side of Kate. The gun was silenced, the shots mere pops.

There was a cry, a patch of blood hovering in the air, another like a small explosion where the bullet exited Bobby’s body.

Kate tried to stand. But the nozzle of Wilson’s rifle was at the back of her head. “Don’t even think about it.”

Bobby’s ’Shroud was failing, is great concentric circles of distortion and shadow that spread around his wounds. Kate could see he was trying to get to the door.

But there were more of Hiram’s goons there; he would have no way through. Now Hiram himself arrived at the door. His face twisted with unrecognisable emotion as he looked al

Kate, at Bobby’s body. “I knew you couldn’t resist it. Gotcha, you little shit.”

Kate hadn’t been out of her boxy cell for — how long? Thirty, forty days? Now, out in the cavernous dimly lit spaces of the Wormworks, she felt exposed, ill at ease.

The shot turned out to have passed straight through Bobby’s upper shoulder, ripping muscle and shattering bone, but — through pure chance — his life was not in danger. Hiram’s medics had wanted to give Bobby a general anaesthetic as they treated him, but, staring at Hiram, he refused, and suffered the pain of the treatment in full awareness. Hiram led the way across a floor empty of people past quiescent, hulking machinery. Wilson and the other goons circled Bobby and Kate, some of them walking backward so they could watch their captives making it obvious there was no way to escape.

Hiram, immersed in whatever project he was progressing now, looked hunted, rat-like. His mannerisms were strange, repetitive, obsessive: he was a man who had spent too much time alone. He’s the subject of an experiment himself, Kate thought sourly: a human being deprived of companionship, afraid of the darkness — subject to constant, more or less hostile glares from the rest of the planet’s population, their invisible eyes surrounding him. He was being steadily destroyed by a machine he had never imagined, never intended, whose implications he probably didn’t understand even now. With a pang of pity, she realized there was no human in history who had more right to feel paranoid.

But she could never forgive him for what he had done to her — and to Bobby. And, she realized, she had absolutely no idea what Hiram intended for them, now that he had trapped his son.

Bobby held Kate’s hand tight, making sure her body was never out of contact with his, that they were inseparable. And even as he protected her he was able subtly to lean on her without allowing the others to see, drawing strength she was glad to give him.

They reached a part of the Wormworks Kate had not seen before. A kind of bunker had been constructed, a massive cube half-set into the floor. Its interior was brightly lit. A door was set in its side, operated by a heavy wheel as if this was a submarine bulkhead.

Bobby stepped forward cautiously, still clutching Kate. “What is this, Hiram? Why have you brought us here?”

“Quite a place, isn’t it?” Hiram grinned, and slapped the wall confidently. “We borrowed some engineering from the old NORAD base they dug into the Colorado mountains. This whole damn bunker is mounted on huge shock-absorbent springs.”

“Is that what this is for? To ride out a nuclear attack?”

“No. These walls aren’t to keep out an explosion. They’re supposed to contain one.”

Bobby frowned. “What are you talking about?”

“The future. The future of OurWorld, Our future, son.”

Bobby said, “There are others who knew I was coming here. David, Mary, Special Agent Mavens of the FBI. They will be here soon. And then I’ll be walking out of here. With her.”

Kate watched Hiram’s eyes, glancing from one to the other of them, scheming. He said, “You’re right, of course. I can’t keep you here. Although I could have fun trying. Just give me five minutes. Let me make my case, Bobby.” He forced a smile.

Bobby struggled to speak. “That’s all you want? To convince me of something? That’s what this is all about?”

“Let me show you.” And he nodded his head to the goons, indicating that Bobby and Kate should be brought into the bunker.

The walls were of thick steel. The bunker was cramped, with room only for Hiram, Kate, Bobby and Wilson.

Kate looked around, tense, alert, overloaded. This was obviously a live experimental lab: there were whiteboards, pin boards, SoftScreens, flip charts, fold-up chairs and desks fixed to the walls. At the centre of the room was the equipment which, presumably, was the focus of interest here: what looked like a heat exchanger and a small turbine, and other pieces of equipment, white, anonymous boxes. On one of the desks there was a coffee, half-drunk and still steaming.

Hiram walked to the middle of the bunker. “We lost the monopoly on the WormCam quicker than I wanted. But we made a pile of money. And we’re making more; the Wormworks is still far ahead of any similar facility around the world. But we’re heading for a plateau, Bobby. In another few years the WormCams are going to be able to reach across the universe. And already, now that every punk kid has her own private WormCam, the market for generators is becoming saturated. We’ll be in the business of replacement and upgrade, where the profit margins are low and the competition ferocious.”

“But you,” said Kate, “have a better idea. Right?”

Hiram glared. “Not that it will concern you.” He walked to the machinery and stroked it. “We’ve gotten bloody good at plucking wormholes out of the quantum foam and expanding them. Up to now we’ve been using them to transmit information. Right? But your smart brother David will tell you that it takes a finite piece of energy to record even a single bit of information. So if we’re transmitting data we must be transmitting energy as well. Right now it’s just a trickle — not enough to make a light-bulb glow.”

Bobby nodded, stiffly, obviously in pain. “But you’re going to change all that.”