Until that moment Dallen had thought of the ship as hovering above the outer surface of Orbitsville — now, with a mind-wrenching shift of perception, he found himself peering upwards. The portal was a one-kilometre lake of blackness set amid Orbitsville's endless pampas, a circular well of stars, and anybody standing at its edge and looking downwards would see the Hawkshead as a huge submarine trapped below the surface. Inhabitants of the Big O lived with stars beneath their feet.

There was a multiple gasp of surprise from the assembled company as the airlock doors retreated fully and a section of the Orbitsville shell became visible at one side of the rectangular opening. It had an alien aspect, one never before seen by human eyes. In place of the inert and non-reflective darkness was a sheet of pale green radiance of an intensity which almost equalled that of the interior sky. The tight was pulsing in a way that made the shell seem alive. Dallen stared at it, stricken, filled with superstitious awe.

"Orbitsville doesn't catch fire for nothing" he thought.

It's all part of a… What frequency of pulsing did Renard mention? Was it once a second? Surety what I'm seeing is faster than once a second…

There was a flurry of activity near the edge of the airlock and the white-armoured figure of a man flew from the ship towards the portal, a line uncoiling behind him. He traversed the open space in only a few seconds, but missed the portal's edge by a short distance and Dallen saw him rebound from the invisible surface of the diaphragm field. He twisted sideways, with the brief flaring of a reaction torch, and managed to catch hold of a short ladder which was clamped to the edge. He went up it, visibly forcing himself through the field's spongy resistance, and other men — dressed normally, moving freely in Orbitsville's airy, sunlit warmth — were seen momentarily as they helped him to safety. There was a spontaneous cheer from the watchers below.

He made it, Dallen thought bemusedly. He made it, and it was so easy, and everything is going to he all right, after all…

"That single line is enough for our purpose," Lessen announced. "We will move along it hand-over-hand, starring with the supernumeraries. Attach yourself to the line with one of the short tethers you will find at your waists. There will be no difficulty, so don't worry. Now let's go!"

Dallen moved forward through the crowd with his weightless human encumbrances, steathed and assisted by willing hands. Ahead of him, figures were already linked to and ascending the line. Captain Lessen, distinguished by red triangles on his shoulders, was positioned at the rim of the airlock, personally checking that each departing passenger was properly dipped to the line. The direct sunlight glittered through crystal helmets and Dallen was able to recognise Silvia just as she set off across the void, closely followed by Renard. She went upwards towards their promised land with the fluid athleticism he would have expected.

The last passenger due to go before Dallen reached the bottom of the line was Gerald Mathieu. While his tether was being checked he gazed fixedly at Dallen, but without any sign of recognition, his face as colourless and immobile as marble. Without glancing into the starry gulf at his feet, he gripped the line and went up it slowly like a patient machine, barely advancing one hand beyond the other. Dallen tried to clip Cona on next, but Lessen prevented him.

"It'll be easier if you go first and bring your wife along behind you," Lessen said. "How is she?"

"Asleep on her feet."

"Just as well. Don't worry — we'll get her there."

"Thanks." With Lessen's help, Dallen linked himself to Cona at the waist, then connected both of them to the lifeline. The crib tethered to his waist was an additional complication, but the absence of weight and rope friction worked in his favour and he found it surprisingly easy to progress upwards with his two human satellites. Mikel had stopped sobbing and was staring placidly through the transparent panel of his ovoid. Dallen tried to concentrate all his attention on the sunlit blue sanctuary above, but there was a hungry blackness all around him and — even more distracting — the Orbitsville shell seemed to have grown brighter. The light from it was so intense as to interfere with vision, but the superimposed pulsing seemed to have increased its frequency to two or three times a second.

At this rate it will soon be continuous, Dallen thought, the first ice crystal of a new dread forming at the centre of his being. What will happen then?

He was now near the midpoint of the lifeline and was so close to Orbitsville that he could see the minutest details of what was happening at the edge of the portal. He saw Silvia and Renard, aided by other hands, force their way through the closure field and stand up, figures greatly foreshortened. Silvia removed her helmet immediately and he saw her breasts rise as she drew deeply upon Orbitville's pure air. She stood at the very rim of space, her face troubled as she looked downwards in his direction. Dallen tried to climb faster and made the discovery that he had caught up on Gerald Mathieu, who had stopped moving and was clenching the line with both fists.

"Mathieu! What the hell are you doing:1 Dallen positioned his helmet close to Mathieu's, looked closely into his face and recoiled as he saw the blind white crescents of the eyes and the fixed, frozen grin.

Captain Lessen's voice sounded dearly above a background hubbub. "What's happening up there?"

"It's Mathieu," Dallen replied. I think he's dead. He's either dead or cataleptic."

"Christ! Can you push him ahead of you?"

"I’ll try." Aware of the people below him on the line crowding nearer, Dallen gripped the nearer of Mathieu's gloved hands and tried Co prise the rigid fingers open. Then he gasped in purest terror as the impossible happened.

The universe split into separate halves.

On Dallen's left, below him, was the partially sunlit bulk of the ship, looming against the spangled backdrop of the galaxy. Down there he could see the red-glowing rectangle of the airlock, with space suited figures awaiting their turn to ascend the lifeline. Lessen was peering up at him, one hand raised to screen his eyes from Orbitsville's sun.

On Dallen's right, above him, was the inconceivable hugeness of Orbitsville itself. Up there, in one segment of his vision, he could see Silvia London and others outlined against a delicately ribbed blue sky. The remainder of his field of view on that side was taken up by the awesome green brilliance of the shell material, pulsing now at a frenetic rate, many times a second.

But in the centre, separating the two hemispheres of the universe, was a layer of utter blackness. It was narrow — barely wide enough to contain Mathieu, Dallen and his family — but he understood with an uncanny clarity that it stretched from one boundary of the cosmos to the other, that it was a dimension apart, at a remove from the normal continuum.

How…? Thought processes were painfully slow in the cryogenic chill that had descended over his brain. How can I understand what I shouldn't be able to understand?

A figure moved in the black stratum ahead of him, perhaps close, perhaps very distant. It was elongated, unlikely to be humanoid, and almost impossible to see — black sketched on black, a glass sculpture concealed in clear water.

Have no fear, Carry Dallen. Its voice was not a voice, but a thought implanted in Dallen's mind, perceived by him in the form of words, but cognisable beyond the limits of language. I serve Life, and therefore you will not be harmed. Let it be known to you that I am a member of a race which has almost complete mobility in time and space. We are the ultimate embodiment of intelligent life. A meaningful comparison cannot be made, but you would say that toe are farther ahead of humans in our evolution than humans are compared to, say, trilobites. We do not apply a generic name to ourselves, but a convenient noun far your use — fashioned according to your linguistic principles — is Ultan. I repeat that we Ultans are servants of Life, and there is no reason for you to be afraid.