Sigma End, Billy Anker’s old stamping ground, was a cluster of ancient research stations and lashed-up entradista satellites sited in and around the Radio RX-1 accretion disc. Everything there was abandoned, or had the air of it. Anything new attracted the attention like a campfire seen in the distance for one night on an empty coast. This was deep Radio Bay. In places like this, Earth ran out of reach. Logistics went down. Supply lines dried up. Everything was for grabs, and the mad energy of the accretion disc lay over all of it. The black hole churned and churned, ripping material out of its companion star, V404 Stueck-Manibel, a blue supergiant at the end of its life. Those two had been locked together for a few billion years or so. This was the last of it: the wreckage of a fine old relationship. It looked like everything was going down the tubes for them.

“Which probably it is,” Uncle Zip’s pilot told him. “You know?”

“I didn’t ask you here for your religious opinions,” said Uncle Zip. He stared out across the disc, and a faint smile crossed his fat white face. “What we are looking at here is the most efficient energy transfer system in the universe.”

That disc was a roaring Einsteinian shoal. Gravitational warping from RX-1 meant you could see all of it, even the underneath, whatever angle you approached it from. Every ten minutes, transition states quaked across it, causing it to spike in the soft X-ray band, huge flares echoing backwards and forwards to illuminate the scattered experimental structures of Sigma End. Go close enough and this mad light enabled you to see clusters of barely pressurised vessels like leaky bathtubs, each hosting a failing hydroponic farm and two or three earthmen with lost eyes, bad stubble, radiation ulcers. You could see planets with ancient mass-drivers let into them, holding positions in the last stable orbit before the Schwarzchild radius. You could stumble over a group of eight perfectly spherical nickel-iron objects each the size of Motel Splendido, set into an orbital relationship which in itself seemed to be some sort of engine. But the outright prize, Uncle Zip said, went to the following effort: twenty million years before mankind arrived, some fucker had tapped off a millionth of one percent of the output of the RX-1 system and punched a wormhole straight out of there to some destination no one knew. They had left behind no archeology whatsoever. No clue of how you would do it. Just the hole itself.

“Deep guys,” he said. “Some really deep guys.”

“Hey,” the pilot interrupted him. “I got them.” Then he said: “Shit.”

“What?”

“They’re going down it. There. Look.”

It was hard to lift the wormhole out of the overall signature of the accretion disc. But El Rayo X came with the equipment to do that, and on the displays Uncle Zip could just make it out, there in the boiling gravitational rapids just outside the last stable orbit: a fragile vulva of light into which the White Cat could be seen propelling herself like a tiny sliver of ice, those curious annular shockwaves still slipping regularly back along her brilliant raw trail of fusion product.