“Too dangerous?” Darya approached the end of the tunnel. She expected to see the energetic vortices, zipping back and forth past the tunnel entrance. What she saw instead was one great pool of swirling black, as though a single vortex had taken up station at the chamber entrance and waited for them there.

That impression faded as she moved to Kallik’s side. The usual circulation pattern was visible, sure enough, and it came from a bloated monster of a vortex. However, it did not fill the whole chamber. There was room for a human — or a Hymenopt — to squeeze past on either side. It might be safe enough, provided that the dark whirlpool did not increase again in size.

“What’s the problem?”

Kallik did not reply in words. Instead she pointed to the black heart of the pool. At first Darya saw nothing, a darkness so complete that instead of delivering illumination the vortex center seemed to draw light away from the eye. After a few moments a faint ghost of an image rippled into that darkness, then just as quickly vanished. Darya was left with the subliminal impression of a distorted cylinder, a long ellipsoid with each end sheared off and replaced by flat planes.

Before she could speak the spectral image came again, and again slipped away.

Again. And again, lingering a moment longer.

“Next time, I think.” But even before Kallik’s quiet comment, Darya knew what she was seeing. It was a Builder transportation system, in the very act of giving birth. Something or someone was being squeezed and corkscrewed through a narrow space-time canal — Darya would never forget the feeling — and any moment now would be delivered into the chamber ahead.

The vortex trembled. Smooth blackness became in an instant a dazzling flash of blue and white. Darya’s suit visor cut out with photon overload. When the visor again admitted light, Darya saw that the chamber in front of her contained something more than the whirling singularity. A dull gray ship of unfamiliar design floated beside the dark whirlpool. And the vortex itself was changing. With delivery over, it was dwindling, tightening, shrinking back to normal size. After a few seconds it faded to gray. At last it became an insubstantial fog, a wraith through which the chamber beyond was visible. And then it was gone.

Darya started forward. She halted when the ship in front of her began to change. Hull plates slid aside, and the smooth gray surface was broken by open dark circles. Darya froze. Even someone from the peaceful worlds of the Fourth Alliance knew enough to recognize weapons ports.

“Ristu ’knu’ik. Utu’is’s gur’uiki.” A blare of warning came from the ship ahead, accompanied by supersonics that raised the skin on Darya’s arms to goose pimples. Something within the ship had recognized what Darya herself had forgotten — that the chamber was filled with air. Breathable or unbreathable, the gases would carry sound signals.

“Can you understand that gobbledygook?” Darya spoke on the private suit channel.

“No. But I think I recognize it.” Kallik was moving slowly to one side, studying the swollen cylinder ahead from different angles. “It is a language peculiar to the worlds of the Cecropian Fringe, where the Federation meets the Communion. I have heard it spoken, but regrettably I have had no prior opportunity for study. J’merlia would surely understand it.”

Perfect. Come in, J’merlia, wherever you are. “Keep still, Kallik. Those are weapons ports.”

“I know.” Kallik had stopped the sideways crabbing, but now she was moving forward. “Permit me to ask something. What is the nearest artifact to the Cecropian Fringe?”

It was an odd time for such a question, but this particular one didn’t call for any thought. Information on all the Builder artifacts was so ingrained in Darya that the answer came as second nature. “It’s the Kruskal Extension — what most people call Enigma.”

“Thank you. Are there inhabited worlds close to Enigma?”

“Three of them. Humans call them Rosen, Lao, and Nordstrom, after the original human explorers of Enigma. But as I recall, there are no humans on any of the three. High mass, all of them, and I don’t think we could breathe the air on Lao.”

“Which is one way of avoiding territorial conflict. But with thanks to you, we perhaps have what we need.” Kallik was still drifting forward, tracked by blunt nozzles protruding from the weapons ports. She switched to external suit broadcast and produced a piercing series of audible but near-supersonic howls. To Darya’s ears it was a painful scream of buzz-saws, nothing like the knotted speech pattern that had greeted them from the ship.

There was a long silence, during which Darya waited to be dispersed to atoms. At last an answering set of screeches came from the ship.

“Excellent. That is Tenthredic, or a variant of it in which I have at least rudimentary speech capability.” Kallik gestured to Darya to move forward with her. “The inhabitants of Lao are Tenthredans. They qualify, at least biologically, as remote cousins of mine.”

“Cousins! But they’re all set to shoot at us.” The threatening nozzles had not moved from their targets, and Darya could see glowing cross-hairs within them. Another awful howl, to her ears like a final warning, came from the ship.

“With respect, I think not. They are merely expressing their own sorrow, alarm, and confusion. I told them who we are, and where they are. That news is distressing to them. Less than half an hour ago, they and a sister ship were entering Enigma to explore it — six hundred light-years from here.” Kallik was heading directly for a hatch on the ship’s side. “A certain apprehension on their part is not perhaps too surprising.”

The stages of Kallik’s logic, as soon as she explained them to Darya, seemed absurdly simple:

One: The original message was in a language used in the Cecropian Fringe.

Two: Since the ship had emerged from a Builder transportation system, it must also have entered one.

Three: Transportation system entry points are associated with Builder artifacts.

Four: The Fringe itself does not contain any artifacts, but Enigma lies close to it.

Therefore, the newcomers probably originated on a world close to the Fringe, and also close to Enigma.

Which made the puzzle of Labyrinth, and the arrival of the ship, no less perplexing. In all recorded history there had been no evidence of Builder transit vortices — until one year ago. Now vortices were popping up everywhere, and making nonsense of all human rules for superluminal transportation.

Added to that, Labyrinth itself was changing again, more and more obviously. Darya and Kallik, on board the Tenthredan ship, were supposed to guide them all back to open space. As far as Darya was concerned, the Tenthredans were more likely to escape by flying their ship straight at the walls than by listening to her. Nothing in Labyrinth was as it had been when they entered. And the changes continued.

She nodded at the solid-bodied, blunt-headed creature poised over the control panel. The family resemblance to Hymenopts was obvious, but with their red eyes, hooked jaws, prominent stings, and banded abdomens of bright black and maroon stripes, the Tenthredans seemed far more obviously menacing than Kallik. There were five of them, and they were all watching her suspiciously with one ring of crimson eyes, while staring at Kallik with the other. The Hymenopt, gesturing to the far end of the chamber, seemed to be explaining some subtle point to the pilot. The Tenthredan was gesturing in turn, and apparently disagreeing violently.

“What’s the problem?” Darya had to change her own role from that of useless supernumerary. “We know that’s the only way out. We have to go through the tunnel, even if it means blasting a way through with the weapons system. Tell her that.”