There was silence for a moment. Then Morrow said, “Are you insane, Uvarov? You’re saying that this galaxy has been hurled like some rock — deliberately?”

“Why not?” Uvarov replied calmly. “The photino birds are creatures of dark matter — which attracts baryonic matter gravitationally. We can easily imagine some immense dark chariot hauling at this fragile galaxy, hurling it hard through space…

“Think of it. The photino birds must have begun to engineer the deflection of this galaxy’s path many millions of years ago — perhaps they were intent on launching this huge missile at the Ring long before men walked on the Earth. And the Xeelee must have been preparing their counter, this loop of string, over almost as great a timescale.”

Now Spinner-of-Rope felt a bubble of laughter, wild, rise in her own throat. She had an absurd image of two giants, bestriding the curving Universe, hurling galaxies and string loops at each other like lumps of mud.

“We are truly in the middle of a war zone,” Uvarov said coldly. “This galaxy, with the bullet of cosmic string aimed so accurately at its heart, is merely one incident among ten million in a huge battlefield. To our fleeting perceptions the field is frozen in time — we buzz like flies around the bullet as it hurtles into the chest of its target — and yet the battle rages all around us.”

Don’t be afraid.

Spinner closed her eyes and thought of the forest dream man, smiling at her from his tree and eating his fruit…

I know who this is, she realized suddenly. I’ve seen his face, in Louise’s old Virtuals…

“I know you,” she told him.

Yes. Don’t be afraid, said Michael Poole.

Louise Armonk asked Spinner to take the nightfighter to the source of Mark’s anomalous hydrogen-band signal.

She showed Spinner some data on the signal. “Here’s a graphic of the main sequence, Spinner-of-Rope.” A bar-chart, in gaudy yellow and blue, marched across Spinner’s faceplate. “We’re getting pretty excited about this. For one thing it’s periodic — the same pattern recurs every two hours or so. So we’re pretty sure it has to be artificial. And look at this,” Louise said. A sequence of thirty bars, buried among the rest, was now highlighted with electric blue. “Can you see that?”

Spinner looked at the ascending sequence of bars, trying hard to share Louise’s excitement. “What am I looking for, Louise?”

She heard Louise growl with impatience. “Spinner, the amplitude of these pulses is increasing, in proportion with the first thirty prime numbers.”

The electric-blue bars were split into discrete blocks, now, to help Spinner see the pattern. She counted the blocks: one, two, three, five, seven…

She sensed an invisible smile. Just like a child’s puzzle, isn’t it?

“Oh, shut up,” she said easily.

“What was that?”

“Nothing… I’m sorry, Louise. Yes, I see it now.”

“Look what’s exciting about finding this sequence of primes is that it means the signal is almost certainly human.”

“How do you know that, just from this pattern?”

“We don’t know for sure, of course,” Louise said impatiently. “But it’s a damn good clue, Spinner-of Rope. We’ve reason to believe the prime numbers are of unique significance to humans.

“The primes are fundamental structures of arithmetic — at least, of the discrete arithmetic which seems to come naturally to humans. We are compact, discrete creatures: I’m here, you are out there somewhere. One, two. Counting like this seems to be natural to us, and so we tend to think it’s a fundamental facet of the Universe. But it’s possible to imagine other types of mathematics.

“What of creatures like the Qax, who were diffuse creatures, with no precise boundaries between individuals? What of the Squeem, with their group minds? Why should simple counting be natural to them? Perhaps their earliest forms of mathematics were continuous — or perhaps the study of infinities came naturally to them, as naturally as arithmetic to humans. With us, Cantor’s hierarchy of infinities was quite a late development. And — ”

Spinner barely listened. Humans? Here, at the edge of time and space? “Louise, have you decoded any of the rest of it?”

“Well, we can figure some of it out,” Louise said defensively. “We think, anyway. But remember, Spinner, we may be dealing with humans from a culture far removed in time from our own — by millions of years, perhaps. The people of such a distant future could be almost as remote from us as an alien species. Not even Lieserl has been able to help us work this out…

“But you’ve made some progress. Right?”

Louise hesitated. “Yes. We think it’s a distress call.”

“Oh, great. Well, we’re certainly in a position to help out god-humans from five million years after our birth.”

“Who knows?” Louise said drily. “Maybe we are. Anyway, that’s what we’re going to find out.”

…There was motion at Spinner’s left. She turned.

Suddenly, the forest-dream man was visible. He was sitting there, quite casually — outside the cage — on the construction-material shoulder of the nightfighter. He wore no environment suit, nothing but a plain gray coverall. His hands were folded in his lap. Light — from some unseen source — caught the lines around his mouth, the marks of tiredness in his eyes.

At last he had emerged. Gently, he nodded to her.

She smiled.

“…Spinner?”

“I’m here, Louise.” She tried to focus her attention on her tasks; she reached for the hyperdrive waldo. “Are you ready?”

“Yes.”

The nightfighter flickered through hyperspace. Traveling at more than a hundred thousand light-years per hour, the Northern edged around the torus of fragmented string loops, like a fly around the rim of a desert.

The journey took ten hours. As it neared its end Spinner-of Rope took a brief nap; when she woke, she had her suit’s systems freshen her skin, and she emptied her bladder.

She checked a display on her faceplate. Twenty jumps to go. Twenty more seconds, and -

Something vibrant-blue exploded out of space at her, ballooning into her face.

She cried out and buried her faceplate in her arms.

It’s all right, Poole said softly.

“I’m sorry, Spinner-of-Rope,” Louise Armonk said. “I should have warned you…”

Spinner lowered her arms, cautiously.

There was string, everywhere.

A tangle of cosmic string, rendered electric blue by the faceplate’s false coloring, lay directly ahead of the ship. Cusps, moving at lightspeed, glittered along the twisted lengths. She leaned forward and looked up and down, to left and right; the threads of string criss-crossed the sky as far as she could see, a textured wall across space. Looking deeper into the immense structure. Spinner saw how the individual threads blurred together, merging into a soft mist at infinity.

The string loop was a barrier across the sky, dividing the Universe in two. It was quite beautiful, she thought — but deadly. It was a cosmic web, with threads long enough to span the distances between stars: a web, ready to trap her and her ship.

And, she knew, this was just one thousand-light-year fragment, among thousands in the torus…

“Lethe,” she said. “We’re almost inside this damn thing.”

“Not quite,” Louise said. Her voice, nevertheless, was tight, betraying her own nervousness. “Remember your distance scales, Spinner. The string loops in this toroidal system are around a thousand light-years across. We’re as far from the edge of that loop as the Sun was from the nearest star.”

“Except,” Mark Wu cut in, “that the loop has no easily definable edge. It’s a tangle. Cosmic string is damn hard to detect; the display you’re looking at, Spinner, is all Virtual reconstruction; it’s just our best guess at what lies out there.”