It was worse than that. He was in his old stamping ground—the gravitation alley at Radio RX-1. The accretion disc roared up at him, quaking with soft X-ray pulses. He was coming in at a steep angle with his fusion torch full on. His coms were getting nothing but the identification beacons of the derelict research hulks—Easyville, Moscar 2, The Scoop: then, very faintly, Billy Anker’s legendary Transubstantiation Station—communications as old as rust, Ed’s past rushing back at him, partial, decoherent, twinked out. Any moment, he would be caught up in the Schwarzschild surf, doomed to do the Black Hole Boogie in a fat tub. “Get us out of here,” he told the direct connect. Nothing happened. “Am I giving orders or not?” he asked the shadow operators. “Can you see my lips move?” They looked away from him and covered their faces. Then he caught sight of a twist of frail light on the inner edge of the accretion disc.

He began to laugh. “Oh fuck,” he said.

It was Billy Anker’s wormhole.

“Come on, Billy,” Ed said, as if Billy was sitting next to him, rather than dead from this exact same adventure more than a decade ago: “What do I do next?”

Something had entered the ship’s mathematics. It was inside the Tate-Kearney transformations themselves, fractally folded between the algorithms. It was huge. When Ed tried to talk to it, everything shut down. The screens went dark, the shadow operators, who had sensed it there days before, streaked about in panic, brushing Ed’s face like very old muslin rags. “We didn’t want this,” they told him. “We didn’t want you in here!” Ed battered at them with his hands. Then the screens fired up again, and the wormhole leapt suddenly into view, very clear and close, a spindle of nothing against the exposed grimace of RX-1.

The whole of the local space of The Perfect Low had, meanwhile, turned into a kind of agitated purple cloud, through which the alien mortsafes could be seen weaving their chaotic orbits, faster and faster like the shuttles of a loom. You could feel the ship shake to her frame with the approach of some catastrophic event, the phase change, the leap to the next stable state.

“Fucking hell,” Ed said. “What’s going on out there?”

There was a soft laugh. A woman’s voice said: “They’re the engine, Ed. What did you think they were?”

In the calm that followed this announcement, Ed hallucinated a white cat at his feet: tricked thus into looking down, saw instead a spill of light emerging like bright foam from Sandra Shen’s fishtank and licking out towards him.

“Hey!” he shouted.

He jumped out of the pilot seat. The shadow operators spread their arms and streamed away from him into the dark and empty ship, rustling in terror. Light continued to pour out of the fishtank, a million points of light which shoaled round Ed’s feet in a cold fractal dance, scaling into a shape he almost recognised. Each point, he knew (and every point which comprised it, and every point which comprised the point before that), would also make the same shape.